Who are my other two? LOL if you want to be taken seriously skip the clown shit. You clearly know some stuff, well so do we. Welcome aboard but gay posts will be ridiculed.
If you're embarrassed to say, then you didn't have to bring it up.
There are more than two possibilities. Someone recently suggested -- maybe not here, I cannot remember -- with an apparently straight face, that Bird ought to be in that group. I have heard ridiculous people suggest that Duncan ought to be.
It also depends on how one approaches the problem -- entire career, peak decade, peak half-decade, etc. How much credit do you give for longevity?
It's difficult to construct parameters for this selection that lead to 3 clear-cut choices that absolutely everyone agrees on.
Just for example, Mikan was the most dominant player in NBA history by far -- he never lost a playoff series while healthy, and retired simply because the game was insufficiently challenging to him. Yet I suspect that he's probably not on your list. I bet Chamberlain isn't either, and he was outrageously dominant by other metrics.