Well the greatest fighter to fight in the last ten years is Roberto Duran, but that aside, Pacquiao has consistently been the best fighter.
In this decade Bernard Hopkins has fought Trinidad, ODLH, JT twice, Tarver, Winky Wright, Joe Calzaghe, and Kelly Pavlik. Was the unified Middle weight Champ and Light Heavy weight Champ. And he has fought 17 times during that span for an average of nearly 2 fights a year with a record of 14-3 (5 KO). Bernard Hopkins is easily the fighter of the decade in my opinion.
Mayweather Pacquiao J.M. Marquez Barrera Morales Lewis V. Klitschko Hopkins Jones Calzhige W. Klitchko Hatton