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.
I’d be more likely to listen to AC/DC without Brian Johnson. He hasn’t done anything wrong (that I know of) and he’s a talented vocalist, but that rasping voice of his makes me wince every time I hear it. Does he gargle glass shards?