Used exclusively a keyboard and mouse until I got a 360 controller a few weeks ago, and I'm starting to favor that over the keyboard. You have ten buttons all within reach instead of being all over the place on a keyboard, and controllers are sort of formed to fit into your hands. (Unless you're talking about an N64 controller, those things are just weird.) Still working on the precise aim things, though, so I'll generally play shooter games with a mouse for better aim.

Depends a lot of what kind of game it is.

Most of the time, I get by with keyboard and mouse controls. Some genres I'd rather use a controller are racing games, pure fighting games, platform games, action games that rely more on response, and jRPGs.

I have a third-party PS3 controller I use for games that support it and use XBOX 360 Controller Emulator for games with controller support that don't natively support the PS3 controller. For some games, mainly FPSes and Minecraft, I prefer keyboard and mouse.

It really depends on the game. For first person games I will use a Keyboard and Mouse, for third person games and platformers I will use a controller

I've only ever played with mouse & keyboard, so I'm gonna have to go with that. It'd be nice to be able to use a controller for some games though. I feel like it'd be a load easier than the mouse & keyboard. n_n

I use a keyboard and mouse for walking-around games (shooters and the like), and a 360 controller for everything else. I love it so much.