Tidus, as everyone has said. He just rubbed me the wrong way.
Sora as well. I swear, if I hear him talk about how you have to use your heart one more time, I'm going to make him a heartless. Physically. With my hands.
Sonic in any game that gave him a voice.
Tails in Sonic Adventure. He was cool everywhere else, but for some reason he decided to go on a "Oh look, I'm helpless and insecure" whining spree in Adventure. He's still my favorite Sonic character, though.
Fox McCloud. Gods I hate that man. That may be spanning from jealousy over my brief fan crush on Krystal, though.
Speaking of Star Fox, SLIPPY. DIE, YOU INSUFFERABLE AMPHIBIAN, SO THAT I WILL NEVER HEAR THAT VOICE AGAIN.
Though you don't really play as him, Issun from Okami. See Tidus.