Well, this top 12(good idea) have some fantastic ideas, and pretty not-so-good ones.
Good: Cody, Guy, R.Mika, Elena, Alex, Birdie, Adon, D.Dark, Ibuki.
Bad: Haggar, Gill, Poison.
Poison could be a cloth for Viper, perfect, even better if they put her win pose too, pole or finger pointing!
Gill isn´t fun to play, from SF3 Universe, I really think Sean or Makoto are better choices.
SF is not a very good place for ladies, but If Sakura made it, and if any of the FF fighters show up, why forget a good series as Rival Schools? WE have there very good fighters, like Zaki and Akira.
From EX, Volcano Rosso(really nasty strikes and a uncommon style), Skullomania(very good character to cover ground fast, risky but great), Pullum(feet strykes from Cammy, Ryu and others, she is not a bad character, but the design could use some work, but just imagining that ink-filter in her kicks, we could build art painted in blood and black)
But the real charm in SSFIV beside the new dolls could be the TAG-TEAM from EX3. A more fluid one, but a tag team mode, with some special changes could insert a fantastic mode in that well build brawler.
Oh, and change the meny to bigger letters, it´s horrible in common TV´s
Sean and Oro! But please, use the SF3:WI Sean, TS Sean went through a lot of unnecessary nerfs...
Seriously. Oro is made of awesome as the stereotypical old guy. A very old guy. (BTW, he's not 1-armed. He just chooses not to use them both to make it fair... yeah... same lame-ass excuse of half the KoF bosses.)
And Sean's mix of Shota Karate and Vale-tudo is the shit. Also, any serious Sean player can tell you that a beach-ball is way better than any stupid hadouken (and it came with a damage buff!).