NBA: Greatest ever at each position

[Phoenix1010]

I liked the recent David Robinson thread, and the discussion on whether Tim Duncan is the best PF ever has got me thinking. You can base this on any mixture of ability and accomplishment that you desire, tweaked by any factors you think are relevant. Here's my list of dark horses for each position (not necessarily my picks, but good for stirring up discussion):

5. Shaquille O'Neal
4. Charles Barkely
3. Scottie Pippen
2. ... This one's locked up
1. John Stockton

As an aside, you can add any current players who you think will crack this list by the end of their careers.