Well i'll go ahead and throw in some info. Mind you, i do not the luxury to playing ALL the characters, but i have taken some time with vids, experience, and conversations with a few well known players.
S2: Chickenwing and wing-zero
S: Algol, Hilde, Voldo, Kilik
A: Cervy, Amy, Asta, Taki, Setsuka
B: Sophie, Cass, X, Mitsu, Lizzy, Sieg, NM, Yun
C: Raph, Yun, Maxi, Tira, Vader, Apprentice
D: Zas, Rock, Talim, Mina
I'll explain why:
S2: It's because we have wing in our name...and we like wings.....but mainly it's because of wing in our name. Deal with it :)
S: They have tools to control you. I'm not saying that none of the other characters do not. But these have better tools then the lower classes.
A:
Cervy- Lows are good but unsafe. That's what holds him back IMO. Also the ease of the use isn't easy at all. You REALLY have to know him to play him. He can't punish alot of things like other characters can. But then again he can punish things that other characters can't
Amy: She's not top. Period. You have to work with Amy to win. She can control you. Yes, she has tools to poke out and outspace you. But her Dmg and SG dmg aren't the greatest of great. This is what holds her back.
Asta: Yes, he can give top characters trouble. Espically if you suck at throw-breaking. He lost his expoitable tools from SC3, but that doesn't make him a terrible character. His 6k is unsafe, but only to certain characters. Evenutally, you'll figure out which characters can't punish his 6K
Taki: 9-frame A. i love it. Other than that, that's all she's really got goin for her. Once you figure out her tech traps and setups, the fight IS Mangeable. Problem is, she does have alot of setups that she can put you in.
Setsuka: i belive she's good, but not top. Then again, i could be wrong. I am basing this off of vids that i've seen and articles of her i've read in this forum.
B:
Sisters: Excatly as told. They rely on YOU to fuck up. If you're good at controlling your game, you can control the sisters.
Mitsu and Lizzy: Mix-ups are the Core of thier game. Guess right, and it's a managble fight.
Yun: can eat your SG, but he can also be linear. That's a problem they'll have to work around.
X: not as bad as people seem, again this opinion is based on vids and discussions. No too much real exp with fighting against one.
Sieg: can eat your SG, he's good. But if a few key things (and moves) were safe, he'd be up there with the A class
NM: good. But unsafe. If he can out-range you, he's better than you.
gotta go back to work ladies :)