"Some men are shallow jerks, some women are as well, and the best way to get through life is to not care so much about who you cannot get along with as about who you can befriend."
--Gabriel Shai Jacobs
So is this like a one night thing, or a life-long partner thing? If it's a one night (or possibly a few nights...), I'd choose the hot one. and if it's for a lifetime (or a long period of time), i'd probably still choose the hot one.
Who wants an ugly chick anyways? plus, just because she's sort of stupid then, doesn't mean she won't develop and mature overtime. and she'd still be sexy when we were old, which is totally awesome!