Its probably because I've grown up with console games more than computer games, but i find controllers much easier to use and far more comfortable.
I mean, controllers are custom designed and a nice and molded to your hands.
Keyboards, on the other hand, were designed for typing, on a type-writer no less. Sure there have been ergonomic improvements here and there, but they are still fundamentally for typing. And the game's control scheme have to be jerry-rigged onto the keyboard. I mean, WASD isn't even nice and properly aligned like the normal arrow keys (on my keyboard at least).
And mice, they are accurate sure. But they're still designed for 2d space. With your forefinger doing so much repetitve clicking, its easy to pick up injuries. RSI, anyone?
So game controller for me, that is, after all, what they were designed for.