Definitely DelPo, as Murray got a ballbasher under extreme wind on his SF and benefited from more rest in the Final to outgrind his opponent in the 5th set.
Yes, Murray's past achievements do make up for this fluke but that is not the question.
djokovic a ballbasher
del potro faced doublefaulterer in that 2009 final
he had the match handed to him by doublefaulterer's choking
emotionalabuserer cried and swore for roddick, but still lost the match
murray had to beat an in form berdych (who only shows up against olderer) in the semis, and beat both the wind and the best hard court player in the world in the final
murray's is more impressive, easily