Simple question: Why?
honestly I haven't gotten that much of a chance to play games on PC but I think i would love it more because you can mod PC games and use console commands. I do love console though because the controls strike me as being easier and I have a bigger screen to play on.
Off topic, but I'd say that's not necessarily true. You can use any wired Xbox 360 controller with a PC (and wireless with a special USB wireless receiver) and there are all kinda of PS3/Xbox controllers made for PC.. heck I'd say there are more choices of controller accessories for the PC than any console.
As for the bigger screen.. I've currently got a choice between playing with my PC hooked to a single 24" 1080p monitor, 2x 22" + 1x 24" 1080p monitors (effectively making it 3x 1080p monitors) OR a single 46" 1080p LED TV.
Related question: can you comment on my above off-topic comment?