LeBron but just barely
Wow. This is a tough one. I strongly believe that much of Tim Duncan's success can be placed on the amazing coaching staff and organization the Spurs have. You can't tell me that if LeBron had been drafted by the Spurs, that they wouldn't have won 2-3 more rings at the very least. That being said, I'm taking LeBron because of his upside. Even after 3 MVPs he's still improving every year until god knows when. This is a really tough one though.