I'm not a PC gamer so I'm not familiar with the keyboard/mouse set up. Even when I did play Starcraft and Diablo, I would always wish I could play those with a more traditional controller (born a console gamer, gonna die one)
My choice was the Xbox360 remote. It feels...right. Much more natural for FPS, no motion gimmick, just pure, simple gaming. If the PS3 controller kept the L and R buttons the same as the PS2 design, I would have been sound-as-a-pound but, no...they replaced L2 and R2 with marshmallows.