I think "Kami" is the most common word. "Kami" or "kami no ke" means human hair on the head. "Ke" means some people's or some animal's hair. If you want to differentiate hair on someone's head from hair on other body parts, "kami no ke" is the best.

kami or kaminoke 髪or 髪の毛 these two words are the best ^^