Michael Bisping. I couldn't stand him until recently when he said TRT is against the spirit of the sport and should be illegal.
I couldn't stand Chael Sonnen until I watched a full interview with him.
I was neutral towards Jon Jones until he acted all holier-than-thou, said Dana would never have to worry about a DUI with him and then wrapped his new Bentley around a street lamp. Him beating some of my favorite fighters didn't help either.