50s: George Mikan 60s: Bill Russell 70s: Kareem Abdul Jabbar 80s: Magic Johnson 90s: Micheal Jordan 00s: Shaquille O'Neal (been in the Finals 4 years and ECF 1 year so far for the decade.)
I'll just say that Magic Johnson was never clearly the best player in the league. In the early 80s, it was Moses and Kareem. In the mid 80s, it was Bird. In the late 80s, it was sort of a draw between Magic and Jordan. And I have a hard time putting Russell ahead of Chamberlain, despite all those championships he won.
I wonder if at the end of this decade people wil look back and feel that shaq really was the best player of the 2000's? becuase he kind of peaked early in the decade like 00-03, and who knows what D-wade and lebron will be like at decade's end? not to mention kobe.