I personally like long and straight hair most of the time.
But as starzk says, girls are not computers or cars which you can pre-order customized according to your taste. It's not that I will like every girl with long and straight hair. Girls are more like paintings or works of art: they are what they are, and their beauty is intrinsic. If you ask a guy why he likes you and he says "I don't know", don't me mad, because you actually hit the jackpot. He likes you because of something he can't explain, something that he feels but that he can't pinpoint. And that's beautiful.
I like both straight and curly hair, it really depends on the girl. Some girls don't look good with curly hair. I love long hair on a girl, but short hair looks nice too, again it really depends on the girl.