1. Sports games. Not because I don't like sports (for example, I love proper football, but I hate the FIFA franchise). The thing with sports games is that I don't think we have advanced enough A.I. to make the game good. Like in FIFA, no matter if you play against Barcelona or some 4th division Norwegian team, the A.I. will play the same. It's like playing the exact same team, but just with different colored shirts.
2. I think we are all saying FPS, but I think many of us are specifically talking about the online component of the FPS genre. I don't mind FPSs, but I abhor online FPSs. In other words, games like F.E.A.R. (that's so long ago!) I like, but games like CoD are utter trash. Games meant to be online shooters first are always crap, but a single-player FPS experience can be quite nice. There's a big difference between the two, almost as much as turn-based and action RPGs. The concept may be related, but the execution is completely different.
3. Simulators. As in, racing sims, flight sims, hunting sims, etc.. I think they're just boring. I don't mean like the Sim-series.
4. Modern Platformers. I love old-school 2D platforming games, like NES-SNES Mario, Metroid, Sonic, Megaman, etc.. But 3D platformers, to me, are just no good. They just don't work for me. I may be one of the few human beings alive who did not like Super Mario 64 or Super Mario Galaxy. I just ... there's an intangible element of the 3D platformer that I just hate. Don't get me started on DK64, the worst 3D platformer ever made.