Wesker: Great pointman, teleporting is fun, generally all around good character
Chun-Li: Lighting Legs assist is god-tier and combos into every assist in the game (including her own). Plus, she's not half-bad for a rushdown character.
Sentinel: Good sweeper, and is just good at everything, more or less. His A assist (Sentinel Force high) goes well with just about everything, and you should be using it at just about every free moment. Plus, with a level 3 X-factor he becomes a godbot of death.