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.
Smashing Pumpkins. I hear their intros and guitars and I’m like “oh cool”, then in comes that screeching loser Billy Corgan, his voice the sound of a thousand fingernails on a thousand blackboards.