You say offense is the most important, because nobody plays D anymore. One could argue "era" here, too.
Did LeBron and Jordon blow away the next best offensive players by all that much? If it's all about offense, then why not Wilt? (He got over 18 rebounds/gm every season he ever played.) Wilt's career line: 30.1 pts/gm/ 22.9 reb/ 4.4 Ast. BTW, he led the NBA in FG% nine time. How often have Jordan & James led the league--combined?
What's the criteria?
Sure, one can argue Russell & Chamberlain were men playing among boys, but that just proves how dominating they both were.
Yes, the game has changed, but dominating is dominating, and to me the best should be based on who dominated the most.
Rings and numbers matter. Getting the most out of your teammates matter. Intelligence, savvy and instincts matter. Yes, the 15 points per game hurts Russell's case, buy I think he could have scored more had they needed him to. I'm pretty sure 22-23 rebounds led to a lot of added points by someone.