Hm. Y’know, I’m not sure.
I think I lean blond at this point in my life, but when I was younger, I was primarily hot for girls with brown or black hair. Redheads have been more of an acquired taste, but I’m now enough of a fan to have been mildly traumatized when Karen Gillian denuded her scalp for *GOTG*.
Hair color just isn’t a big (conscious) factor for me. When I’m scanning someone for physical attraction, I generally go face > voice > hairstyle > ass > vag > boobs, but I’m not paying a ton of attention to the colors of anything along the way.