First year out, and he's already made it debatable. If he's not this year, he'll definitely be next year. Kobe achilles, Wade getting older, Harden will be taking the thrown. Almost everyone has Harden top 10 already. I think he'll be top 5 in 1-2 years.
I think healthy DWade has the edge right now because of his play on both ends of the court. However, considering Harden's age he'll definitely be the best in a year or two.