360, because playing games like Assassin's Creed just feels wrong on PC, I prefer the console versions of Mass Effect, Rockstar don't seem to make PC games anymore, and I also play a decent bit of online FPS on it. Don't judge me, I grew up using controllers and keyboard/mouse equally.
PC also gets a lot of play-time, almost entirely because of steam and it's evil sales. Those $5 and $7.50 purchases add up...Also, I play a decent amount of RTS, and lesser known indie games that will probably never be on console like Mount and Blade.
Would get a PS3, mostly just to play with my friends, but the default PS controller is just really uncomfortable for me. Feels like it was made for someone with smaller hands. Also, just not sure what I would get on it, other than games I already own on PC/360, just so I can play them with friends. Not saying PS3 has bad exclusives, heavens no, just not too many that appeal to me, and just about every game I care about is multi-platform anyway.