I calculate my P4P lists differently based more on talent then accomplishments. Of course accomplishments are factored in but honestly these are who I believe the 10 best fighters in boxing are who are at least champions. Guys with more accomplishments (Marquez, Bradley) though are given the benefit of a higher position.

1. Floyd Mayweather
2. Manny Pacquiao
3. Timothy Bradley
4. Juan Manuel Marquez
5. Paul Williams
6. Sergio Martinez
7. Andre Ward
8. Juanma Lopez
9. Wladimir Klitschko
10. Chad Dawson
11. Nonito Donaire
12. Lucian Bute
13. Fernando Montiel
14. Chris John
15. Celistino Caballero
16. Yohnny Perez
17. Shane Mosley
18. Poonsawat Kraetingdaenggym (the best fighter from Thailand in the last 10 years imo even though I haven't seen his last fight)
19. Arthur Abraham (I have him ahead of Dirrell because I think he beats more fighters then Dirrell)
20. Miguel Cotto

You could pretty much arrange 4-20 however way you want to imo.