Obviously, beauty is something that automatically attracts the attention and turns people on, but smart people are logically sexier. They're stimulating in so many ways.
Yay, we're all deep people! Hahaha, but yeah. Perfect example: my boyfriend can be really charming, but until I got a real look at his brains and who he is as a person, I always shot him down (before we started dating).
For long term I'd have to take the brains...although I admit I don't give a damn for short term.....although there is a limit...I'm not screwing someone with a rock for a brain.