Greater fighter: Gennady Golovkin, Vasyl Lomachenko, or Sergey Kovalev

Jacobs is at least a weight class bigger than GGG (more like two) and his claim in that fight is speculative at best. Haney is a full natural 154lber while Lomas never been more than an average 130lber at best. Kov never fought any relevant fighter who was notably bigger than him, he was a large and well proportioned 175er who typically enjoyed a size advantage. GGG and Loma were both always small or very small compared to their opponent outside of the Brook fight (whose barely even smaller than GGG) and the Rigo fight.

How I would rate them ability wise (roughly ofc) would be something like this-

Relative skill level: Loma>>GGG>=Kovalev
Physicals/Intangibles: GGG>Loma>Kovalev
Overall: Loma>GGG>Kovalev

If you solely judge based on their resumes and give no context beyond name value I can maybe see the case for Kovalev. This is just how I see it personally.

 

I will have this opinion till I rot and die:

Lomachenko is the top 5 P4P ever. If everyone was the same size and at their peak Loma would be in the top 5, he might even be the most skilled boxer ever

 

Greater in terms of accomplishments: Golovkin, clearly and by far.

Greater in terms of raw eye test and H2H ability: has to be Lomachenko, who was simply extraordinary in his matches and who made guys that people were glazing heavily at the time, look like chumps.