I have to say that I am partial to artificial coloring that is done well. Emphasis on that last part. Pastel blue is probably my favorite while most shades of green, especially the bright shades, make me slightly queazy. Natural hair color is good too, I'm not picky, but people with colored hair are generally a little off (Sorry for the generalization) so I don't have to worry so much about scaring them off with my non-sequiturs and odd topics of conversation.