Why am I using a controller? It's simple: it's more comfortable, buttons and actions are easier to execute and I don't get finger cramps from using the keyboard...which as I've said, wasn't designed around gaming. Sure I could buy a different keyboard that would help with that but I've already got a controller here and I might as well use what I can.
Most people in this topic come off as only having used keyboard + mouse on PC games. Try a controller on for size for once. Sure your accuracy won't be as pin-point because of the thumbsticks insensitivity but everything else about it is better
you do know that majority of games have used controllers before i go a xbox and as ps3 and play FPS on it and i'll still say keyboard and mouse is better and you got more precision.