Lilac. I swap between lilac and pink on a fairly regular basis. My hair IRL is dark pink - I went grey very early (22) and as I'm self-employed I don't need to look "corporate" anymore, so it's pink from May to October and purple from around Hallowe'en til after Easter. Makes me much happier than grey/white!
My hair is the lighter blonde right now. I haven't unlocked Shampoodle's yet, but I had brown hair before and a friend kept telling me my tan made me look bald, so they let me use their Shampoodle's.
Dark Green("Color of the forest"). When the game first game out I actually had dark green hair irl. I really like it so I probably wont change it any time soon.