The drift only has 30fps at 720p. Its only waterproof to .5 meters, it has zoom, but thats kinda retarded for a helmet cam. It has a screen, but so does the gopro now. It also has poor color saturation compared to the other two.
The Contour is not waterproof, has a crappy lens, has 60fps at 720p has bad "waves" problems, and the color is a bit over-saturated in my opinion.
The GoPro is really waterproof, has a BATTERY WARMER, has 60fps at 720p, has in my opinion the best color saturation, and better low-light capabilities than the other two, has tons of mounting options,
Considering the GoPro has better lowlight, and a battery warmer, it is pretty much the best choice for skiing.
But of course my opinion is bias, since I own a GoPro, and have never used the Drift.