1. Duncan
2. Malone
3. Garnett
4. McHale
5. Hayes
6. Nowitzki
7. Barkley
8. Jerry Lucas
Now the problem comes with guys that blurred that line because they played multiple positions Willis Reed, Dennis Rodman, Dave DeBusschere, Bob Pettit, Amar'e Stoudemire, Bob McAdoo, and Dolph Schayes. All played time at PF but a bunch of time at another position.
When Willis Reed played PF alongside Walt Bellamy as his center it could be argued he was a top 5 PF ever. Rodman as a PF is arguably a top 10 PF ever but played the SF position for years in Detroit. Pettit was a center for as much time as he was a PF but is there any denying that as a PF he belongs in the top 10?