Hate might be a strong word, but here we go.
1) The Kingdom Hearts games. I'm told they're actually decent but I can't get past the fact that it's full of Disney characters, and I refuse to like anything involving Disney. Give us back the Muppets!
2) All visual novels. These shouldn't even be classified as games but they are. Stop making them, Japan, please.
3) Licensed games. No exceptions. Ever since playing this absolutely awful Spider-Man game for the SNES many years ago I've stayed far away from any licensed game. This causes me to miss out on potentially good games like Batman: Arkham Asylum, but that's the way it is. First impressions usually decide how I treat an entire genre and Spider-Man is what defined licensed games for me.
4) The Paper Mario series. I'm sure the games are great in their own right but I hate them on the basis that they're nothing like Super Mario RPG. I know it's unfair. Too bad.
There's more, but I'm tired.