#3 Players that are often overlooked in this duel of sorts
Wilt "The Stilt" Chamberlain averaged 50 points per game for a full season and recorded the only 100-point game ever in NBA's history. It can heavily be argued that his length and athleticism would fit well in modern-day basketball as well.
Another great talent worthy of an honorable mention might be Oscar Robertson - the walking, talking triple-double of the vintage era, someone Westbrook so dearly chases on a daily basis.
There have always been better rebounders, passers, and scorers in the game since time immemorial, but the approach-to-approach conflict in the name of who's better between Michael or James rests on the fact that they are both complete packages.
Sure they are not the 'best' players to have played the game, but the term 'greatest' will always oscillate between the couple for numerous reasons.