I consider Silva the GOAT at the moment. He is destroying people while the new breed of MMA fighters are making old legends seem one dimensional. Hell, silva moved up a weight class and destroyed people there. GSP can't end fights in his own weight class
Both cleared their divisions but, Silva did most of it while toying with his opposition. GSP had to work his ass off. Also, I think we can all agree Silva has a better chance at beating Jon Jones than GSP has at beating Silva.