M. Bison?
Pfft. He's a punk. People always try to do his lame sliding trip and against inexperienced players you could actually get them stuck in the corner.
Guile used to be a pain, because his special moves could both be set up the same way (hold down and back), and you could fire sonic booms until the guy tried jumping it, then he would flash kick you.
Though I learned how to spam Ryu's much faster fireball, and it was gameover for him then! Plus while going up in the Dragon Punch you are invincible (I once Dragon Punched a fireball with zero health left to avoid getting it, since blocking would have killed me. Made me feel l33t). Much better than Sagat's lame, wannabe Tiger Uppercut. Ken may be a wannabe follower too, but at least he took the time to learn the mad skillz0rs in the correct way. Sagat is a little baby. Ryu whoops him!
Though I think Balrog (in Turbo, since you could play him) was the worst. Ugh did he suck.
Dhalsim, the stetch guy? Sucks.
Ahhhh, so many memories.