I think a watermark looks good, done tastefully. Not a bright red blob of text over the subject's face. That said, I've never watermarked any of my pictures. None of 'em would be good enough to steal. xD
Generally speaking, I like watermarks because they let me find more pictures done by that person.
facebook page // nh cosplay events
COSPLAYS IN PROGRESS
Constructing : Soren (Fire Emblem), Fox (RWBY)
Upgrading : Sheik (armor), Cloud (wig and armor)