Sports games. A few of them are alright, like some of the Mario ones which are, at least, creative. Realistic ones and ones that release the same game every year with graphical updates and new rosters like Madden and such should go take a bath in a vat of hydrochloric acid.
Also, gritty, brown FPS. In Call of Duty, I get the feeling that I'm playing as a soulless drone. I also find the graphics unappealing. That's one of the reasons that I prefer Team Fortress 2; each class is well characterized, and everything is bright and colorful.
I particularly enjoy Racing games, either.