I really like 4. That's a strong image. The rest, I'm not so crazy about. I think the one subject (sweater) is too interested in showing off for the camera. This is fun, but can get repeatative.
The second subject never connects with the camera. You get the sense he is unhappy to be there. No eye contact (except in 4, but the feet are the subjects) and I fail to connect with the fun they are having.
One the other hand, the lighting is spot on! I am guessing but it looks as though you used a soft box high and to camera left. Possibly a relfector to camera right? Either case, its perfect.
I love the contrast, not over done and well balanced using a white background.
-Nick