In no order:
Jon Koppenhaver (War Machine, mainly hate him for calling himself that. I mean War Machine, what the actual ****?)
Honourable mentions: Bobby Southworth, Ed Herman and Sean Sherk
I don't really dislike many fighters though tbh, and it was quite difficult to come up with a few I don't actually like, or at least have a slightly negative opinion of anyway.
You really don't like Dan Henderson? wow....