Platformers make up maybe 75% of my game library, with 3D platformers being my favourite genre. The AAA market is leaving me hungry for that though, so many of these are on the PS1/2
I want to say "action-adventure" is 2nd, but that genre name sounds like a cop-out. Pretty much when I say that, I mean something like Zelda or something similar.
JRPGs I guess make up 3rd, but many of them are Kingdom Hearts and Pokemon games. Only WRPG I have is Skyrim, and I don't play it religiously.
Then I have a few hack and slashes, which I enjoy to an extent (depends on the game). They tend to get repetitive.
Open-world sandboxy type games are alright, but I tend to be picky with them. Just depends on the game. Infamous and Assassin's Creed 2 are good though.
Over the last 8 months I've been playing shooters, but that's only 4 games (not counting Portal 1 or 2). I would only play a shooter if it has some sort of interesting story or mechanic. Those 4 games are Black Mesa, Spec Ops: The Line, Bioshock 1, and Bioshock: Infinite. They also must have an easy mode because I suck donkeys at them.
And then a few miscellaneous games that don't fit evenly in one genre, like Shadow of the Colossus and Journey.
Genres I won't or rarely touch:
-MMOs
-Fighting games
-Strategy games
-Sim/God games
-Point and Click adventure games or games that heavily utilize backwards adventure game logic
-Horror games (not because I don't like them, but because I'm a coward)
-Racing/driving games
Mind you there's always room for exceptions.