For me, pound for pound is half what you have accomplished and half what I think you are capable of going forward. That said, Golovkin is probably somewhere between #4-#6 pound for pound. Gonzalez, Kovalev, Ward and Wlad should probably be ahead of him.
I'd put him #4 or #5, depending on Ward. If Ward fights a legit LHW next, then he's #4 and GGG is #5.
Fighters who COULD be above GGG in a p4p list based on CURRENT dominance and previous 2-3 years of resume: - Roman - Wlad - Kovalev - Inoue Crawford is close to these 5. Nobody else comes close.
I think that p4p Golovkin is ahead of Kovalev. But straight up head to head, Sergey punches Gennady's ticket. Just too big and powerful.