I look at these things:

-Individual talent/game
-Individual accomplishment
-Impact on the game
-Status vs Contemporaries
-Length of that status
-Team Success/Accomplishments/make up
-Winning
-Historic impact (the most subjective so least important consideration but a good differentiator for those closely aligned)
-Era/Circumstance (The further back in history we go, the more greatness is discounted as over time the game develops and advances)

Looking at all of those things in totality:

1) Jordan
2a) Kareem
2b) LeBron
4) Wilt

5-10 (in no order); Russell, Magic, Bird, Kobe, Shaq, Duncan
11-15 (in no order); Big O, Dr. J, Moses, Logo, Dream
16-20 (in no order); Zeke, Malone, McHale, Baylor, Gervin

By the time their careers end, I'll have guys like Curry, Durant, Harden, maybe Westbrook in this group.