Chrono Trigger
Crono 8.5/10: Forced most of the game, but why not, he's excellent. Very fast, good damage dealer, combos with everyone. Just BEING forced helps him, because he tends to learn techs earlier than the others who bop in and out. He could have more utility powers, I suppose, but if you only have one healing/utility power, why not make it revival?
Marle 7/10: The first and best healer, and she also has support abilities, so obviously she's going to see a lot of use. But, CT isn't a game with no other serious options (HI RENA) and I ultimately didn't use her all the time.
Lucca 3/10: Lucca is awesome... but not in gameplay. Honestly, she feels like the weakest/least-useful member of the cast. IIRC her lategame damage is good. To get there she'd have to be used regularly, though, and I didn't.
Frog 5/10: Useful at first, but kind of falls off as you get other options.
Robo 5.5/10: Kneejerking him as being better than Frog? He seems better at crowd control than Frog without really losing much.
Ayla 7/10: Joins fairly late but is really good. Charm for stealing, Kiss for healing, and the best physical attacker (aside, I think, from Crono?).
Magus 7.5/10: Magus is only this low because 1. everyone else except Crono (who I feel is a smidgeon more useful) and Lucca (who I feel kind of sucks to begin with) has at least some kind of healing, and 2. he joins late and learns his techs slow. Still, variety of elements + powerful magical attacks + excellent speed + non-fail physical.
Fire Emblem Lords, Dancers and Other Unique Classes
Ike(9) 10/10: Every time I've played it he's been the runaway MVP, dwarfing everyone else in power by a margin I almost never see in a game. I'm given to understand this is RNG screw for others (Oscar) and RNG blessing for Ike, but it is what it is. Even when he's "weak" he's not exactly Brigandine-Lance weak, having to be babied; he's the fourth-strongest character until Shinon and Gatrie leave (and IMX starts catching up to Shinon by the end of that stretch) and second-strongest prior to promotion. For me he was already the MVP as soon as he promoted (he very nearly soloed the battle with Jill's father on Hard, for example).
Mist(9) 3/10: Gets a point for being useful if she's babied to promotion. But you have to go out of your way to raise her and Rhys is more than adequate.
Reyson(9) 7/10: Only as good as the people around him, but those are pretty darn good by the time he joins. .5 extra because he nets you the Knight Ring.
Elincia(9) 5.5/10: She can be very good, but she joins late, requires a degree of babying and doesn't have anything like the decisive advantage the way she does in FE10.
Micaiah 6/10: -9.5/10 for FAIL. But much as I hate to admit it, she's extremely important in the Dawn Brigade sections of the game, and even when the parties join up she remains a useful caster for long-range bombardment. On the flip side, she ALWAYS requires protection and she takes an endgame party slot that could be put to far better use.
Rafiel 2/10: I wouldn't want more than one Heron and he's not as good as the others. Useful when he's your only Heron, I guess?
Black Knight 6/10: Very hard to rate, IMO. On the one hand, he's obviously far, far beyond other characters when he's available. On the other hand, using him more than the bare minimum leaves the Dawn Brigade even worse than they usually are. On the gripping hand, you do, if not NEED to use him, at least struggle a lot to avoid it.
Elincia(10) 9/10: Now we're talking! Elincia starts out better and has a more comfortable level curve, quickly reaches a point where she needs little or no protection, and provides both mobile healing and powerful attacks. If she were available for a greater percentage of the game she might crack the 10s.
Leanne 1.5/10: Not!Reyson Heron. Manages to be extra-frail even by Heron standard, which is saying something. Also, not really critical for the sequences when she's the only Heron available.
Ike(10) 7.5/10: Instead of being unbelievably better than everyone else, Ike is now merely very good. Oh, he casually pwns many of his own, pre-endgame chapters, but that's a mix of level edge and weapon edge; by endgame he isn't even the best fighter. On top of that, he's not available in quite a few sections of the game.
Mist(10) 7/10: Inferior to Elincia in basically every way, and she has to be built up to be really good. But, it's easier to build her up than in FE9, she's better when she IS built up, and "inferior to Elincia" is not even a knock considering Elincia is the MVP.
Reyson(10) 7.5: Just like FE9 Reyson, except you actually have a choice (and he's the clear leader) and he has more overpowered people to give extra turns to, making him even more of a force multiplier.
Sanaki 6/10: Best mage unless you really, really leveled Micaiah, and maybe even then? Feels about right. But she's not available that long, and mages generally aren't as good as fighters anyway. Her main use is as long-range artillery.