Final Fantasy 7:
Cloud Strife: 7.5/10. Yeah, game best PC. Best overall stats, good weapon selection, and good Limits outside of his Level 2's (and Blade Beam isn't THAT bad). Problem is, as was said, this is FF7, so there's too much genericness to really get much higher.
Barret Wallace: 5/10. Mind Blow is a cool limit for someone like Rapps for completely gunning down offense, and he's a good ranged tank. If only there was more reason to care about that in FF7. I'm a big undecided on his Ultimate; on one hand, its easy to build, but it comes at the cost of possibly gimping other PCs since you're giving him a lot of the high level Materia. Its also gotten later than most Ultimates (HAS to be gotten right before Hojo, so its pretty much Disc 3 only.)
Tifa Lockheart: 7/10. Strong limits, and the only character who can actually run physical twink set ups THAT DON'T SUCK the entire game, let alone using a 4 Slotted Double Growth Weapon, and Master Fist is good if you want actual Materia Slots + Growth, and raw damage, and one of the best Ultimates in the game if you know how to set up around it, due to a Higher Mult and runs off a stat you can keep relatively static (well, when its maxed anyway)
Aeris Gainsborough: 3/10. If she was a permanent PC, she'd probably be closer to 5/10. As it stands, using her does hurt your team a little as its that many kills she's stealing from other permanent party members for more limits. She does make a good mage, not so much cause of her magic (which doesn't hurt), but because of the Fairy Tale as I noted, but that gets undermined later on. Her later limit hype baffles me cause to get to the first really interesting one (Fury Brand), you're stuck with the SINGLE WORST LIMIT IN THE ENTIRE GAME, and without massive grinding, she's NOT getting Pulse of Life/Planet Protector. And no, I don't respect her physical with the Umbrella. Her game worst strength offsets it, and has NO MATERIA SLOTS.
Nanaki "Red XIII": 5/10. Lunatic High is a cool early limit if gotten before Time+All, Seraph Comb makes him a strong physical fighter on Disc 1 WITHOUT compromising his Materia slots much the way the Umbrella does (not to mention on a character who doesn't have Game Worst Strength), gets the first Double Growth weapon in the game I believe, and otherwise a flexible PC, who beyond the Seraph Comb ownage stage, doesn't stand out much. Well, ok, Stardust Ray is pretty bad ass, but unfortunately, its guarded by BLOOD FANG >_<
Yuffie Kisaragi: 5.5/10. All Ranged Weapons is cool, Limits are generally good outside of her Level 4, and probably the best overall Ultimate in the game due to how it likes it ignore Multiplier Penalties (I believe it ignores 4x Cut's damage*0.67 per hit factor, so it actually is 4x damage!)
Cait Sith: 5/10. A better Aeris, in the grand scheme of things. Silver M-phone = Fairy Tale+, stats with that on basically become "Aeris with more HP", Slots basically gives him Pulse of Life MUCH earlier if you can get timing down, and to top it off? He's a permanent PC.
Vincent Valentine: 3/10. Back Row weapons worth something, being one of the only PCs with linked Double Growth slots is neat, and Sniper CR + Deathblow is kind of OK for MPless damage, though doesn't last. Limits are cool early game, but don't last. Outsider is a cool weapon at least, though doesn't completely make up for his ass-tacular ultimate.
Cid Highwind: 4.5/10. People are underselling him a bit, cause I said before, the Dragoon Lance is really bad ass and deserves mention for how early it is. Though, that and his neat Game Best Growth Weapons are really all he has going for him, as his limits are generic, and doesn't have any real gimmick factors outside of that.
Since its FF7, I can't give anyone lower than a 3, barring maybe Aeris due to her nature, but at the same time, I can't give anyone much higher than a 7 (Cloud got 7.5, yes, but that's cause he's really undeniable game best PC, but not by enough to garner him a full extra point)
Final Fantasy Tactics Monsters:
Behemoth: 2.5/10. Dark Behemoths are okay at their one-dimension, but it's still one dimension.
Bird: 4/10. I randomly fanboy over birds due to the mobility and three decent options (stone, strong physical, ranged magic chipping). Deal with it.
Bomb: 1.5/10. Bad.
Bull Demon: 1.5/10. You want to use a Behemoth if you're considering this. Or heck, various others have comparable, PA, like...
Cat: 3/10. A much less mobile bird with more HP and a bit of range on their stone in exchange for accuracy. Losing trade but they're kinda okay.
Chocobo: 4/10. Reds are very solid ranged snipers. Black has some occasional use as a ferry, too, though terrible stats.
Dragon: 3/10. Okay all-around, nice if you can snag a weakness, but still stuck with all the usual monster limits.
Floating Eye: 2/10. They can fly but not really do much great. Randostatus woo.
Ghost: 3/10. Well drain touch rapes bosses somewhat at least.
Goblin: 1/10. Are awful.
Hydra: 5/10. Hey Tiamats are actually legitly badass, murdering things dead while being tanky and having fly. As good as a monster gets, obviously.
Marlboro: 1.5/10. Bad. Wooo crappy status option.
Skeleton: 1.5/10. Goblin with a ranged option.
Squid: 1.5/10. Mind Blast is so much more useful in enemy hands than yours.
Tree: 0.5/10. Oh god trees. Not a 0 because they're easier to get than mimes.
Uribo: 1.5/10. No mobility or durability, but hey they have some power and status if they reach an enemy alive at least!
I don't do this often, but I pretty much agree with Elfboy, and trust his opinion more than mine on this subject!
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Regarding Midgar Zolom? First off, I have to note Grefter that her level 3-2 Limit is also invincibility (Planet Protector), it just doesn't have the "Free Megalixir!" effect Great Gospel has.
BUt more importantly, you can get Beta ASAP without using Aeris. She's probably best as the 3rd PC there just cause of the extra back up healing, admittedly, but she's not necessary.
To do so, give Barret Elemental + Fire on his Armor, Sadness Status, and for extra insurance, the Talisman (Or whatever +10 Spirit accessory is called); the first two are mandatory, the latter is not. Obviously, give him Enemy Skill too. Additionally, don't give him any more Magic Materia than is necessary lest you'll compensate his HP.
Put everyone in back row, have someone NOT Barret cast Poison until Midgar Zolom is poisoned, and use Sense on him once (I believe this makes the Assist function display his HP now in addition to his name when you're targetting); play defensively and let Poison do all the work until he's about 20% of the way til dead. HIt him once, he'll go into the uncoiled mode. At this point, its all luck, since if he Ejects Barret, you're screwed, and you need to time things right such that after being hit with Beta, kill him immediately (you'll probably have a Limit ready), or Heal Barret, and wait for Poison to finish him off.
Yeah, its a pain in the ass and can take a while, since there's a luck factor (see the Ejection part), but its certainly doable without her; Healing Wind is an extra insurance policy there, nothing more.