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.
Keene has struggled a lot with drugs over the years. He’s notoriously difficult to work with. Its a shame because he’s an incredible musician. I really hope he can get his shit together.