I use keyboard mostly because I've always use keyboard. I never had a console, so I learned to play and mouse (when I start playing, it was the time of Commander Keen, Rick Dangerous, Wolfenstein 3D, King Quest, Land of Lore, Dune 2, Flashback... etc). Later, to compensate the lack of console, I discovered Emulation... But still, always with keyboard (and believe me, Megaman with keyboard is a pain in the arshe). So now, when I got super meat boy, I gave controller a chance... But was unable to play with it.
So keyboard forever