RTSs. Specific games include Age of Empires and Starcraft. I don't have much problem getting into the "build a civilization" thing, I like doing that so I do ok. Nor do I have a problem with using armies to take over the universe. I don't like that so much, but I'm reasonably able to make plans, assign resources and execute them, so I do all right.
My problem comes when I have to do both at once. To me, it seems as if I'm trying to play two completely different games, and I have a lot of trouble switching back and forth in real time. And because you can be attacked at any time, it's a situation where I can be forced to switch at any time.
So yeah, not so good at those. Unfortunately, my best friend is very good at them. I've played AoE games against him where we added two other computer players on Hard difficulty, and he had no trouble beating all of us together. It's one thing to be embarrassingly bad in front of strangers, but it's a complete new level of humiliation to be that bad in front of a friend. Plus, it means we can't play coop on a lot of fun games
The good news is that I am better at shooters than he is, so I have some redemption. I got within shouting distance of competitive level on L4D2 Versus when I played regularly, and he just couldn't deal with the ambush tactics. He also can't get through MW games without sniper-clearing everything before he moves, whereas I can go into the heat and come out the other side.