As an MSX user, my motion-control vote goes to...

I have to wonder though how relevant this poll is to MSX. The Kinect controller delivers a depth field and an RGB image. The MSX doesn't have the processing power to get something useful out of these in real time. So you'd have to process it outside the MSX to detect for example the position of hands and feed those coordinates to the MSX. A similar approach would be needed for PlayStation Move. The Wiimote however returns a manageable amount of data per second, if I recall correctly.

Assuming you create a way to connect one of these systems to MSX, with or without external processing, what would you do with it? You could write new software for it of course, it would make a great demonstration at an MSX fair. But not many people will build such a connection system if there is little software for it and not many people will write software for it if so few people have the system. So the only real motivation to build it would be "because I can".

A way to reach more people would be to add support in an emulator for these control schemes and then try to interface that with existing games. However, the question is how such an interface would work. You could make a scheme where the position of your hand controls the virtual joystick directions and moving your hand towards the screen presses the virtual joystick button. But I doubt it would play very well.

In my opinion you cannot just take a new control scheme (such as motion control) and attach it to existing game play (such as the arcade-style games on MSX) and expect the result to be fun. Some companies have tried this on for example buttonless touch screen phones by using either an on-screen d-pad or tilt control, but it just doesn't give the player the direct feedback that you need for these games. What I mean is that if you push a joystick in a direction or press a cursor key, you immediately feel that you have indeed selected for example "go right" as the action, even before you see the sprite move.

Bugger motion-control. I'll just take the Wii for the low price, good composite support, and retrogaming-oriented library. (Now if they'll just approve La-Mulana...)