My pick is Five Finger Death Punch and the obvious answer is Ivan Moody. The guy radiates that alpha-male wannabe energy and it definitely rings through all of the songs he has written and performed with this band. The guy is just a prick and a self-victimizing asshole.
I think he’s the primary reason FFDP is mocked so badly.
Along those same lines, Limp Bizkit because of Fred Durst. They still would have been pretty mid, but maybe I wouldn’t go out of my way to skip their songs when they sneak onto my playlists.
Fuck Fred Durst. Fucking riff-stealing crybaby.