As far as achievements, mainstream exposure, talent, longevity, basically all categories. overall who has been impressive?
tough call, Loma is the fastest 3 weight world champion and his performances have been superb but hasn't ever unified, whereas Usyk has won the WBSS and become undisputed. i'd lean very slightly towards Usyk.
Prior to the WBSS it was undoubtedly Loma but now I'd lean to Usyk. Breidis and Gassiev are great wins.
Both have had amazing careers thus far & I suspect both are future HOFers.. I'd go Loma though. Linares, Rigo, Walters, Marriaga, Sosa, GRJ, Pedraza, Salido*, Martinez etc over 3 weights... Making them quit! Sensational... Loma is a showman of RJJ, Hamed etc proportions.. Usyk less so... Loma is pure boxing porn, Usyk though a purists wet dream too isn't quite as talented IMO