Mouse & keyboard. Everything else is just slow and clumsy, and I don't see the Wii changing that much. A mouse translates my movement into corresponding movement of my aim on screen. The Wii does this as well, though I can imagine turning quickly will be problematic. Heck, the team behind Red Steel already said you can't turn as fast as with a mouse, but I won't deny the Wii will be a big improvement over analog sticks. The speed and accuracy of a mouse is unparalleled though which is a large part of why I've all but given up on console FPS games. They tend to be slow and plodding to make up for the inferior control scheme.

I will say though, that the Dual Shock is by far the best console controller for an FPS in my opinion. The four shoulder buttons mean you don't have to take your thumbs off the analog sticks very often. A big problem I have when I do play Halo is that I essentially have to stop aiming for a fraction of a second to use the melee attack, and that fraction of a second has made the difference between a rifle butt to the side of my friends head, or a shotgun shell in my face.