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 feel the same about a lot of metal. I often really love the instrumental portion of lots of really heavy metal, then often the vocalist opens his fucking mouth and ruins it.
To each their own, I suppose.
Could you give us some specifics?