I love Nate and Nick Diaz, but Masvidal is coming into his own right now and I think he's moving into the upper echelon. He's just a more versatile fighter at this point. It's sort of amazing how much the DIaz Bros have been able to win with their skillsets. They're essentially volume boxers that have good jiu-jitsu. Neither one hardly ever throws any kicks at all, and besides an occasional Judo throw, trip, or single, they basically don't even go for takedowns.
Nate Diaz is in the top 5 most submissions in UFC history, but if you actually look at how much time he's spent on the floor it's surprisingly little. He just boxes guys up with body and head shots until they take a panic shot on his legs and he subs them. For guys that don't have the most impressive wrestling, either offensively or even defensively, they've gone a long ways. Especially Nate.
But Masivdal is the total package. Good hands. Smart combos. One punch KO power. Impressive wrestling sequences. Good front headlock choke submissions (ie. darce and anaconda chokes). Good passing and back attacks. Demian Maia even said Masvidal is the best guy he's been on the floor with in his UFC career. That says a lot.