Well the Mist village may not really be known but everybody shown from it has been a villain so far. Zabuza may have been evil but he wasn't the heartless kind of guy as obviously he regretted stuff, and showed he cared for Haku. He even kills the guy who hired him along with a bunch of others in one of the coolest scenes making up for some of the stuff he was trying to do in the Arc. It was probably Haku that changed him that little bit from the Demon he was before. Not to say he wasn't still bad just the kinda of villain that actually cares for someone but doesn't want to admit or show it. Even if it was only Haku and nobody else. Zabuza trying to take over the Mist is better than what most of the other villains are trying. Madara, Sasuke, Orochimaru all they want to do is destroy Konoha for no good reason at all. Pein...he's just a bit crazy and wants to destroy everything.