I don't really like the persona that Ronaldo tries to play sometimes. In particular, his goal celebrations where he lifts his shorts up and shows off his legs, or when he makes those "breast squeezing" gestures in the air, or when he "shushes" the crowd and points at himself, or even that pose he does before taking a free kick. It all seems very attention-seeking. The fact that he has his own "museum" of his awards as well...
I know he's one of the best players of all time, but so is Messi, who manages to show a lot more humility and class than that. I think Neymar used to be a little bit like that as well, but he seems to have toned it down a lot in order to fit in at Barcelona.
I also don't like Pepe, Sergio Ramos, Arbeloa, Diego Costa, and players who always look as though they're trying to get into a fight.