I have a number of friends who are both pretty and down to earth. Try the nerd-girls. If you find one that isn't mega-crazy, she's probably reasonable, plus with girls it's harder to find an ugly one than a pretty one.
It's because pretty people in general don't need to do anything to get liked. Because they're pretty, they don't have to try to stand out.
It really just depends on who you determine to be 'pretty' or not.
Ever notice that the people with real personalities are usually the more overweight people? It's kinda like that. They have to put themselves out there to get liked.
I've met one, then she changed. But, i do believe there are more people like her out there. They're the best people you could've ever had in your life.