21 on my list. I think Mayweather will overtake him by the end of his career though. Mayweather definitely IS the better fighter but Whitaker has the better resume with greater career defining wins.
#20 is generous, because the OP is asking about "P4P" ratings. - That specifically implies power. I'd put Whitaker around #10 for skills & boxing IQ, maybe even higher, but P4P he's quite a ways down the list.
Pernell "The second coming" whitaker. He was magical in that ring. Unbelievable ability. If he had power he would have made a run at the greatest. Personally, my favorite boxer.
I love Pernell but very let down by the fact that he didn't implement certain styles into his fighting tactics/