None I think their all good villains

All XD

Unalaq

When unalaq starts trouble......

*Sings the song while bolin punches unalqs face

Definitely unalaq. He was the one who destroyed all the past avatars.

Vaatu was a damn joke. Change my mind

I only don't like one thing about one of them: Amon's psychic bending skill. It bugged me to no end to watch him stand there while Mako and Korra flew around the hallway.