The key to this question is what 'first' attracts you to someone. It may sound shallow but as a guy trying to decide who to approach at a bar or social gathering - looks end up being the starting point.
But as we all know - if there isn't more to it than that, it isn't going past the first drink or dance. I guess that's why I met my wife through friends - not just picked out of a crowd.
Because we had common friends - there was a common sense of values, and for us that has been the key to 22+ years of wedded bliss.