I like MMORPG's. I used to play the first lineage, but then, I couldnt afford it. I havent played one since, but when I played lineage.... it was sooo much fun.
Second favorite would be FPS... then a regular roleplaying game.
RTS hands down they aloow u to control a variety of units and on some the blood and gore from fighting is always cool. I like fps to but they tend to bore me after a while.