He lasted longest out of the 3, not sure that means he’s the best. When they were all playing, Fed was better at 2/4 slams and even at RG, Nadal better at 2/4.
Yeah, it's sort of like Roy Emerson. He held the grand slam record from 1967 to 2000.
He had the most grand slams, but he was just an all-time great player. He was never considered, to my knowledge, as the greatest player ever.
Novak Djokovic will hold the grand slam record, but he's just going to be like Roy Emerson.
The order is Federer, Nadal, and then Djokovic.
And I'm not even much of a Federer fan, I'm more of a Grigor Dimitrov fan (and Arthur Ashe is my favorite player). But obviously Roger Federer is the greatest tennis player ever. And then comes Nadal, and then Djokovic.
Although, you could probably still put Rod Laver in the top three. And Pete Sampras.
So the real order may be: Federer, Laver, Sampras. Or Sampras, Federer, Laver... and then Nadal, and then Djokovic.
Anyway, Djokovic will have the most grand slams, but that's it.
And Nadal's opinion on Federer seems perfectly reasonable.