I honestly don't like nail polish on girls at all. Maybe shine though. But most guys really won't be looking at your nails. If they're clean and well trimmed then they can look really great. But I find coloured nail polish distracting and unnatural looking.
Nail polish (if you arnt just going for the natural look) should match your outfit. For instance black looks great if you are wearing black and have pale skin. Red looks great matched with red lipstick and a complimenting accessory (say a scarf or shoes).
There really isn't a colour which is intrinsically better than another.
(Voted D for versatility, and because I generally prefer the natural look).