Who's the most arrogant guy in MMA? How about the most humble?

I would definitely agree with you in saying that GSP is one of the most humble. Lyoto Machida is also very humble. Despite sometimes being quite y mid fight (see how he dropped his hands and showboated a bit in his second fight against rich franklin) Anderson Silva is very respectful and humble, as is rich Franklin for that matter. As much as i love his character and his style, Rampage can be very arrogant. BJ Penn can be pretty bad too, he trash talks a hell of a lot. Overall i would say most humble Georges St.Pierre, most arrogant Frank Shamrock or Bisping before he was knocked out by Hendo (that taught him some humility).