Overall, it depends on what color works best for the guy. I've been interested in guys with all different hair colors. I do have a thing for black hair though... but if the black hair didn't look good on the guy, I wouldn't like it. Make sense?
As for me, my natural hair color is light brown, but I was a redhead all through high school. I'd like to go back to red someday soon. I think it actually looks better with my face and complexion and looks more "natural" than my real hair color.
I have black hair that looks a bit brown depending on the lighting. But I've been attracted to men with almost all hair colors. My preference is probably blond or brunette but it really depends if it suits the guy in general.
I prefer blonds and brunettes, voted blond though. By that I mean real blonds not the fake ones. fake is always bad imo. if I had to choose between a fake blond and a real brunette I'd always go with the brunette. Same deal with the fake boobs and everything else.. looks un attractive in my own opinion.