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.
Axl Rose seems like a dick, but would it have been the same band without him? His really unusual voice is a lot of the appeal of the music imo