Mine is probably Simulation. I love simulation games, I love games like SimCity, The Sims etc.
I also really like puzzle games.
My least favorite is probably Sports games (except for Wii Sports which I oddly really love) or Third Person Shooters. I'm also not the biggest RPG fan.
Top 3 favorite games: Super Mario Galaxy, The Sims 2 (PC), The Legend of Zelda: The Wind Waker