Well, I can't pick 2, but I like brown hair, any shade really. But it honestly depends on t he woman. Some women look weird when they dye their hair darker or lighter, but other women can look good with that different color. I also don't really preference hair color as any kind of factor in dating. My two past attempts at girlfriends both had blond hair. (Maybe this is why they failed. Just Kidding. )
Blonde, but I'm not sure why. I think the other colors are cool too, but for some reason blonde hair always catches my eye -- it doesn't mean I will automatically think the girl is attractive, just that her hair catches my eye.
And you didn't ask, but I always perceived women who are fake blonds to be stupid and attention hungry. Maybe unfair, but its like instead of them starting at a neutral, they start at a -10 intelligence and have to prove their way out of it. Same would go for guys who are fake blonds, though I don't see many of those, lol.