I'm not denying Fed is top of the GOAT debate but you just can't deny the fact that he picked up a lot of majors when he had no competition. I'd kill to have seen Nadal for a year or two with one shot wonders like Roddick as his greatest rival.
As for Stan, he's beaten peak Djokovic for each of his slams so he's not had it easy either. Nadal, Murray and Djokovic just genuinely have had to battle far harder for their slams as compared to Fed steamrolling it against poor opposition for 2 years. Fed is still GOAT though and I won't deny that.
Likewise you can also argue that Rafa picked up a lot of his slams at Roland Garros at a time when he didn't have any clay court competition. Although Rafa gets a lot of credit for his head to head record with Roger - and justifiably so - few ever question the lack of any great clay court players who played during Rafa's time. Five of his French Opens came from beating Federer - a non clay court specialist and the remaining ones came from Mariano Puerta, Robin Soderling, David Ferrer, and one from Djokovic - again a mix of vaguely anonymous one/two year wonder players who disappeared and Novak who wasn't a clay court specialist. There was no Gustavo Kuerten, Carlos Moya, or Sergi Bruguera - all former world number one clay courters who played in preceding eras, to give Nadal a serious challenge on clay
Now this isn't to demean Rafa's accomplishments. He's easily the best clay court player in history and probably the 2nd best player of all time in terms of slam results, but just as some say Roger didn't have competition earlier in his career, you can make a similar case that on clay - Rafa's best surface where he accrued a vast majority of his slams - he didn't have adequate competition either. In fact 6 of his 9 Roland Garros titles came from beating non-Clay court players (arguably 7 if you include Soderling).
At the end of the day, all we have are the results history has given us and the only thing that will be remembered three, four, five decades on, and the only thing players will aspire to reach is Federer's slam record.