I game on pc, a measily Presario 750US notebook. Man, this thing is nothing but a portable webtv (remember those?). lol! don't get me wrong, its fast enough, but forget about good gaming without adding new hardware.
PC is definitely my favorite thing to game on, I truly believe it always has been the best machine to play games on and always will be.. (go keyboard and mouse!).. Also my trusty Xbox 360 gets the job done for certain types of games that either aren't out for PC or just aren't good on PC (and yes such things do exist)...
PC only, I don't own a console anymore. Last console I has was a PS2. I much prefer using a mouse/keybpard to any kind of controller. I just played Halo 2 on Xbox last weekend with a bunch of friends and I sucked so bad. I can't even use a controller, it's hard as hell look around with the little thumbpad thing.
I game mostly on the 360 but since it red ringed (has been shipped back to microsoft be back in 2 weeks hopefully) on me i game on my pc just waiting to actually get some games worth it for my pc though