Kovalev has proven he can compete against world level opposition, so its only fair to use his resume to gauge his over all skill. GGG has mostly beat regional level opposition, so while he looks impressive KO low-qulity mostly regional opposition, its hard to guage his skill set since he's not used it against top level comp.
Kovalev. Because he already had the chance to obliterate the so called "names" in his division, while they only talk about fighting GGG and then run with their tails between their legs. If you go with potential, then Golovkin is the better of the two and so is Loma.
Exactly what is that world level competition? 50-year old B-Hop and Pascal? I guess that's better than Golovkin's but is it really two levels up as people keep saying??
Cleverly, Gabriel Campillo, (49 year old Hopkins-still competitive, can defeat 98 percent of all lightheavies). Pascal 2x.