I'm not saying that it's the only factor, just the most important one. Sure, there are definitely girls who are very attractive who aren't very smart, or just average, but I could never see myself in love with such a girl. Could I fall in love with a plain but fiercely intelligent girl? I'd like to think so, but I honestly couldn't say for sure.

In reference to the OP though, intelligence trumps delicateness/strength - I couldn't care less which of the latter the girl in question is (Outside bizarre extremes such as steroid-pumped weightlifters and that kind of thing, but then I'm guessing they were never being considered anyway).