Yeah, 5 consecutive at both Wimbledon and USO is really impressive, one of the historically unique feats in tennis. It's not as rock solid as Rafa's FO record but I have to say, I don't expect to see anyone repeat 5x in a row at USO and Wimbledon in my lifetime either.
Fed will always have a case for GOAT, just because of peak play and dominance, he had probably the best 4 year run ever. He did have some bouts of really impressive in his old (tennis) age as well but was marred by inconsistency, some if caused by injuries in 2013 and 2016. You can see that he's still relevant just by the fact that even in this forum, people still talk about Fed all the time (whether fans or detractors) despite him being retired for 3 years now.
Nadal and Novak have their claims too of course, with Novak's IMO still being the strongest despite everything. Nole slam, won literally every big tourney in tennis there is, Slam and weeks and YE#1 records. Yeah he had a few weaker gens which made it easier for him to be so dominant at 30+ but still, that can't take all the shine of his ridiculously complete career, it's damn near perfect CV.