I hate him.
Yes he had the greatest run as WW champion. But that doesnt make him the greatest WW of all time. GSP right now would beat the Matt Hughes of 2005 10/10 times. Therefore he isnt the greatest WW of all time. The answer to that question is GSP.
mma as a whole has grown so much since then....hughes is the best ww of all time b/c he beat top fighter after top fighter time after time...gsp has yet to do so and until he does, he'll be consider the 2nd best ww of all time.