Instead of saying my favorite and being done, I'll offer additional info by stating what i think about each hair color.
Blonde: Can be a good hair color. Looks good on certain people. Unless you have very bold or vibrant eyes and long lashes, your light hair will wash out your facial features. I'd totally date a blonde, but its not my favorite hair color.
Red: 1. Natural red (ginger) - I'm sorry, but its typically not attractive to me. If i see a really gorgeous ginger some day, i might change my mind. But to this day i have never been attracted to a ginger. 2. Unnatural or dyed red (darker one) - Its fine by me. It typically doesn't look good on pale girls or really tan girls. You really have to have the perfect skin tone in order to pull off red hair.
Brunette: Probably my favorite. It looks good on anyone. Pale skin or tan skin. Dull eyes or bright eyes. I love brown hair because it is dark enough to highlight facial features without looking dull. Brown hair has the same effect on a face as eyeliner has on an eye.
Raven (black): Looks good only on tan people. On pale people the contrast is too overwhelming and quite frankly makes them look sickly. But i feel just as positively about black hair on a tan girl as i do with brown hair.
Less common unnatural colors (blue, green, pink, purple, silver, etc.): Love it! It makes a person look very fun and vibrant. Although brown is the best natural color, i feel very positively about these colors as well--especially blue or silver. Unfortunately though, the only time i really see girls with this hair color are when they are emo--which is something that usually drives me away because i had a very scary and stressful relationship with a suicidal girl in the past.
red heads are the best!! i love the freckles and the way there hair changes colour with the seasons :) plus all the ones i have met have this really sarcastic, spity personality and im a real fan of a girl who answers my sarcasm with more sarcasm