I guess it would depend on the girl and her features (skin color,hair color, etc.) but if I just had to pick one it would be yellow. Eveytime I have seen a girl wear yellow it looks nice and I never really see a lot of girls wear yellow, so that might have something to do with it.
But I think it would depend on a girl. For example, I know I can't pull off red very well. It makes me hair look red and my skin look red, and it's just awful on me. I think it would depend on your hair color and skin tone.