I'm for personality, can I make you laugh? Are you a happy person or more serious? Do you like people or are you suspicious of them? Hair color is like the border or frame of a painting, it's not the painting itself. It's all about how well two people work together.
No preference but I've always dated brunettes so maybe that says something. Always prefer natural colours over dye jobs.
Dye jobs can be fun imo, but only if you go over the top. On the other hand, I wouldn't go for the rainbow look myself.
The fierce red hair is actually my favorite. Of the two blonde though. But it isn't really what I look for. But a redhead girl with bright green eyes could make me do anything for the record