FE Fates: Done all three campaigns more or less. I do have the final map of Revelations to playthrough, but I want to do bonus crap and plan to make super kids so am doing that right now. Total time played through all 3 campaigns totals up to about 120 hours (about 50 on Nohr, 30 on Hoshido and 40 on Revelations).
I'm not in love with it as much as NEB is. In particular, I am with Fenrir in that I think part of the charm of FE is the simplicity, which makes it much easier to determine for example what maneuvers are safe and what isn't. In essence, any time you lose a unit, you could have math'd it out and planned around it. I felt that Fates over complicated some things such as having weapons that all changed stats, weapons with innate debuffing effects, changing the weapon triangle completely so that now one weapon can actually score two weaknesses and two strengths , etc. But the most notable change of course were the maps; at least the Nohr ones. I didn't mind them so much, but I think if you disliked XF maps cause you thought they were gimmicky, you will hate the Nohr campaign. Every map has a trick behind it and you often have to use the trick in order to win (otherwise, life gets very difficult). Some of these are easy to work with, others, not so much (sup Wind Map).
The game is still good - but maybe a little over ambitious. I wouldn't worry about skill load outs for the most part to those that didn't want to try it because of that. I can confirm, that after playing through all 3 campagins, they are relatively minor on enemies and are more of a player based customization system. You can totally ignore it if you want and it won't hurt you all that much. What does stand out to me in the end are the maps. Most of them are very cleverly designed and as mentioned before, you can tell just from playing it that the designers have thought this through. The levels often have individual skirmish spots that contain 3-5 units and the game is designed such that no one type of unit can hold all of them in the game. This gives you an incentive to try out different units, and assemble teams where everyone has a unique role instead of just "use your best units" all the time. I feel that the map design gets in the way of this at times, but YMMV. Like for example, they fixed some polish issues such as no Ninja reinforcements. But the map design may make it such that it moves your units around or otherwise gets them stranded in some fashion that it puts you in a really bad spot (and the first time through, you might not know how the gimmick works or when it kicks in).
Positioning is a lot more important. Not just due to Dual Attacks and Guard stancing, but also from certain passive benefits from characters. Again, you can play without these but it's a player advantage, so you're obviously better off trying to take as much advantage of it as possible. Where you place your units (and when) can make all the difference as well.
Of the three campaigns, overall, I am most satisfied with the Revelations one. It has some nasty maps, but you also have a lot more units (and good ones at that! Sup royals) so there are more options to explore and the difficulty gets mitigated somewhat by that, which is genuinely cool. Nohr was a little too difficult for me on Hard (I had to go back to Normal around the last couple of maps) while Hoshido was a little easy. There's a mid-game stretch in Hoshido where the difficulty was pretty bad, although the late game maps pick up (that Hans map sticks out). Overall, pretty good game! Still think Radiant Dawn is probably the best of the series, but Fates is pretty damn solid and is probably slightly better than Awakening. Beats all the GBA FEs pretty easily. Some thoughts on the units I used/recall with text shrunk to avoid text walling and gameplay spoilers:
Avatar/Corrin/OK/Meeple/Bob: Whatever you want to call the avatar, he/she is pretty solid. I went with +speed boon and -skill bane in one and -res in two others. -Skill is probably still the best bane for practicality reasons because all those skill books you get, you can pretty much just feed him/her. Res on the other hand, has several good candidates. Great offense at all points, can even do some tanking with the Dragonstone if you wish. On promo, Hosh Noble is kinda unimpressive on skills but staves gives you a better utility role. Nohr Noble makes you better on offense (even though you get worse offensive stat boosts) by adding magic to your repetoire, giving you a great skill in Draconic Hex and ups your defenses, which is important if you want to use the avatar for holding down a line/drawing fire at any point.
Kaze: He has a really bad strength cap (15 at tier one) and his defenses are awful. However, he's blisteringly fast and incredible Res means he's a great mage slayer. The 1-2 range on Hidden weapons is really what makes Kaze good since he can avoid enemy attacks and debuff them even if his damage is kind of shoddy. Against mages, he just tends to one round them while taking little to no damage. Gets better in Revelations due to unique hidden weapons on both routes, letting him hit weaknesses on many enemy types. Can't do point combat or tank, but he's good support if nothing else.
Silas: I have some mixed feelings on this guy. On one hand, he's pretty good defensively between his Defense and HP. And god knows you need some good defensive units in the Hoshido campaign. On the other hand, his speed is really iffy. He tends to be really good if he gets adequate enough speed or really bad if he doesn't as just doesn't have enough defense to reduce damage to the point that doubling wouldn't hurt. In Revelations, he tends to fall into the latter category since he joins with only 15 speed or something at Level 18 (still higher than Xander but...). I had to Speedwings him to make him more usable. He did however, come with great stats everywhere else (Res in particular was much higher than expected). Once he's up to pace, he's great as mentioned. Dual weapons before promo, decent enough defense to tank a hit, high mobility, etc. Could fit a multitude of roles then.
Azura: Uh...Songstress is okay I guess? They will never be as good as in FE7 since they can't dodgetank or have unique buffs or be as good as Reyson/Herons due to mobility and refreshing multiple units. I actually got better use out of Azura as a Sky Knight. I spent the other two campaigns trying to use her as a Songstress and it just doesn't really work. As a Sky Knight, you can at least use her as offense on point and she's great at that. Plus, she's a lot more mobile and on promo, staff utility is great. Amazing offensive growths, awful defensive ones sans Res. A good candidate for your Robes/Dracoshields.
Shura: I used him for a bit; he starts pretty great but mediocre to bad growths means he won't ever really become a staple. A worse Anna overall, but has good utility at the time when he's relevant (about 3-4 chapters).
Jakob: The better character from your retainers. He's pretty solid across the board. Passable defense and offense and staves! He does tend to fall behind after some point, but he never felt truly obsolete IMO. Staff utility is great when you can take a hit and do other stuff to help around too.
Felicia: Not as good as Jakob even on early join. Just...the physical stats are really bad (strength/defense/HP). She does get better when the Flame Shuriken arrives. Then she gets actual offense and can score KOs. Still remains as a constant physical liability though and runs screaming from anything with 1-2 range. Before then, she's a staff bot but can heal more than Jakob. I would almost always use Jakob before even considering using her though
Gunter: Is Capt K and Eph merged into one package. 10/10. Must use unit. In all seriousness, he's the actual Jeigan. Bad stats, bad growths but he's critical in the opening chapters since he can actually take a hit and dish it back out too. Later on, you can use him as a pair up bot, but I found that I was usually better off devoting a slot to someone else.
Mozu: Donnel-. However, she's easier to get started (Archer reclass means she doesn't need to be melee). Just doesn't end up as overstatted ever as Farm boy. Still pretty solid and a good bow user, which are actually more relevant this time around. Used her in all three campaigns actually!
Sakura: Hey, its a healer who's defenses are total garbage! I mean, she's not a tank, but she won't die to a stiff breeze. On promo, even gets a mage class as well, where you can put that meaty Mag stat to use. I used her as Priestess in Revelations actually stuck to Bronze Bows for a while so she can pick up the Shining Bow. At that point, she was one of my best units. Could ORKO a lot of stuff from it. Her strength won't be really all that impressive so its pretty easily the worse choice.
Hana: Massive offensive glass cannon. Her HP is abysmal and her Def isn't much better. However, being really fast and having really good strength means she's often able to drop whatever she is attacking. The Samurai starting skill really helps solidify her role as mainly an on-point unit. Dropped her pretty quick in Revelations since that type of build doesn't really buy into my preferences. But she's good at what she does.
Subaki: Uh...not sure. I've never gotten good growths out of him. My current plan in Eugenics!FE is to get him levels as a Samurai because his speed growth is pretty awful. He does however have pretty high base Def and supposedly good growths there. He's no Haar, but he's mobile and can take a hit in the opening chapters, which means he's useful there. Just dropped pretty early after.
Hayato: I think he's supposed to have good Speed, but the one time I used him, I wasn't really all that impressed. I dropped him pretty quick in Revelations since I really didn't need more point characters. And in Hoshido, he's really awful (joins at Level 1 when your dudes are like Level 15). I guess you can map grind him out, but eeeeeeeeeeh
Takumi: Archers are pretty good overall due to being more relevant from flying enemies, more weapon options and being a part of the triangle now. Takumi is probably the best though because of his unique bow, the Fujin Yumi. With it, he doesn't get Terrain penalties, so functionally, he's like a flying archer (can't cross impasses though). This is better than you would think since you can put him into positions where he can reach the enemies quicker or even safer by being on defensively sound terrain. Also, his stats/growths are in the right place (Str/Speed) and his defenses are total garbage either! Royals kinda good, and this will be a recurring theme.
Hianta: Unlike Hana, who had a definitive niche, I have no idea what Hinata is supposed to do. He got pretty bad level ups along the way...is he supposed to be like a tank SM? Anyway, dropped pretty quickly on both routes.
Oboro: She's actually pretty good and reminds me of Nephenee. Not all that strong starting out of the gate, but once caught up, she's a great asset. Defensively capable, offensively capable and doesn't have any truly crippling weaknesses. At the same time, she's not outstanding in any one direction, but can fit solidly into the army. Better in Revelations when you get Javs. In Hoshido, she almost always has to attack at 1 range.
Hinoka: Flyer older sisters are OP in this game. She makes a great flying RES tank and has great offense. You can also reclass her to a Spear Fighter to get better Defense but that comes at the cost of mobility. On promo, staff utility makes her one of the best units. MVP on Hoshido route. Just think if the game gave her a legendary weapon.
Saizo: Pretty solid, all things considered. I think this is because Ninja adds to his speed and he has already good defense growth naturally. Physically tankier and the better ninja of choice against physical units compared to Kaze, but worse magically.
Kagero: Unlike the two male ninjas, she's great on offense, but pretty bad defensively (as bad as Hana). So 1-2 range point character more or less. I find less of a reason to use her since I'm often strapped for defensive units versus offensive ones, but she's pretty decent all things considered.
Ryoma: Well, his defenses are kind of bad, but his raw evade (especially on point) is so good, you might not even notice. Then of course, his offense is godlike. 1-2 range weapon that adds 4 strength and 1 Speed makes it such that he often doubles and even one rounds things nicely. The only complaint really is that he's not as mobile to his counterpart in Xander and worse raw defense.
Elise: Elise is basically Hana once she promotes. Really good magical offense, but can't take a hit if her life depended on it. Does have staff utility though and hitting a better defensive stat often makes her more relevant despite being so physically frail. Her other promo choice (Maid) is uh...not good. Seriously, hidden weapons running off that strength?
Arthur: Oh look, it's Knoll with axes. So the perfect Eph unit. I found him pretty bad, but JUSTICE MUST LIVE ON etc. Would use him just for the VA.
Effie: She's alright when you first get her. As NEB noted, she's good at scoring OHKOs thanks to her passive and massive strength. Eventually enemies start doubling or she starts missing the ORKO and then she's pretty bad. You most likely have to fast promote her to General and then get to Level 5 so she grabs Wary Fighter to keep her relevant at that point. Just on Nohr, your experience is limited, so I dunno if this is doable without DLC...and if you want a wall, Benny is a better option.
Beruka: The passive is pretty great (+4 free damage essentially) and she has flight. The stats though are a lottery. Unlike the knights, she doesn't have access to it normally and she can either be Str/Def/Spd screwed, either one really sucks. Strength is the easiest to overcome though, thanks to the fact that she does have access to Trample, and her personal skill already adds damage that you should be utilizing when you can. She did turn out really good on my Nohr file, but got speed screwed in Revelations (that and better competition).
Selena: The better Hero of the Hero dual, although Heroes aren't that impressive. Better defenses makes it a pretty big deal. I don't recall her being particularly good, but she also wasn't awful either.
Camilla: MVP in Nohr route. Aside from joining with excellent stats, yet "under" levelled, she also has flight. She's also arguably MVP in Revelations because she keeps the same advantages + early join time too compared to her siblings. Her main competition there is Hinoka, but Hinoka joins later, so yeah. Oh, natural Trample and Savage Blow too for support. Again, flying older sisters are OP.
Niles: Has all the speed in the world, but the strength and defenses are off. Truly, probably best used like a thief unit, since I tried putting him on offense and was pretty disappointed. Adventurer was probably the better promo in hindsight since staves. But Shura joins at about the same time, so alas. Dropped eventually. In Revelations, joins really late so was pretty irrelevant at that point.
Odin: Needs to be reclassed almost immediately because his offensive stats are like flipped around. Once he gets caught up as a Sam, makes for a decent point unit. Again, not overly impressed, but ARGH MY ACHING BLOOD etc.
Leo: He doesn't look that impressive, but 1-2 ranged magical offense is pretty damn good. I've gotten great use out of him in both routes he's available on.
Benny: 6 Speed. Holy god, that is awful. However, Benny's main role is as a wall. He starts with 21 defense and it gets better pretty quick. You have to almost quick promote him though since he lacks Effie's strength and he's going to get doubled by everything that isn't a general (and that just leads to bad times). Used him in Revelations to round out my defenses and yeah, he does what he's supposed and is great at it.
Charlotte: The polar opposite of Benny. Massive offense, but bad defenses, although you have to work towards getting the offense started. Special shout outs for being the best mom for any physical oriented kids however. Never really used her since again, I had plenty of good offensive units so I didn't need to add another one my active party.
Laslow: The worse Hero of the Hero dual. Pretty bad defensively and lacks a truly defining niche. Dropped pretty quick after doing a quick comparison between him and Selena.
Peri: Can serve somewhat defensively and isn't bad offensively. Just overall, feels mediocre-ish.
Xander: Kind of wish I used Xander now in Nohr. Anyway, I avoided him initially because his starting speed is bad (15 at 20/4? Ew). But Seigfried gives him+4 Def, and it makes him really tanky. Oh also, it's 1-2 range. A good tank for sure since he also gains mobility. Speed eventually curbs itself I think, but a good candidate for those Speedwings if Silas didn't turn out badly. Used him in Revelations though, and yeah, he's a core part of my deployment.
Kaden/Keaton: Objectively similar. Kaden's more of a mage slayer, Keaton's better against physicals. I got more use out of Keaton though in Revelations and avoided both in their individual paths. Beasts are pretty decent since they can't get screwed over by Weapon Triangle. Kaden has an advantage in that he can dodgetank almost everything after a while doubling. Keaton's more average, but can take a hit physically and generally keep rolling.
Scarlet: Really good in the one campaign where she's available. Flight, defensively solid and good offense! She could deployed with little leveling before hand - just very solid. Lack of support options does hurt somewhat, but she's solid for long enough that it tends not to be significant long term.
Flora: If she had Felicia's speed, then maybe. As is though, egads. About the same speed as Xander but no way to really boost her defenses means she's almost as frail as Felicia. At least she does have strength though so she's not a total sitting duck. Staff utility means she's never truly bad, but yeah, she's...not good.