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.
I don't quite agree with your assessment there...the sport has evolved so much in the last few years, I mean 20 years from now, are you gonna discredit Michael Jordan as the best ever just because some new player is at the top of his game? Matt Hughes was the best and most dominant fighter of his time, he was ahead of everyone. You can't really measure greatness by comparing head-to-head skills since the sport is evolving so much.
Edit: didn't see your post there aaronnyman
"Right kick; hospital, left kick; cemetery" - Mirko "Cro Cop" Filipovic