Roger Federer says there is no GOAT because players from different eras had different priorities etc.
Pete Sampras says Federer is the GOAT for now, but that his head-to-head vs. Rafa is an issue.
Andre Agassi says Rafa is the GOAT even if he once said Federer was the GOAT.
John McEnroe says that Rafa is the GOAT even if he once said Federer was the GOAT.
Rafael Nadal says that either Federer or Laver is the GOAT, and that it will be hard to improve upon their accomplishments.
Boris Becker says that it is impossible to compare across generations even if Federer can check off a lot of boxes of success.
Rod Laver says Federer is the greatest of all time.
BB and RF: GOAT = Null Set
PS: GOAT = RF w/ concerns
AA and JM: GOAT = RN but was RF and maybe was PS before that
RN: GOAT = RF or RL
RL: GOAT = RF
This is one of those perennial questions that is not going away anytime soon. If one was dividing territory between the two it would look something like this.
Roger Federer: Total Weeks and Consecutive Weeks at #1 (this edge shrinks a bit every week Rafa is #1), Most Grand Slam Titles, Most Grand Slam Finals, Consecutive Grand Slam Finals, Consecutive Grand Slam Semifinals, Consecutive Grand Slam Quarterfinals, metrics focused on consistency and longevity such as consecutive Slam events played, Year End Titles (6-0 for Federer vs. Nadal), Grass Court Winning Streak, Hard Court Winning Streak, Tournament Final Winning Streak, First Player Since Borg to Win Wimbledon Five Consecutive Times, First Player Since Tilden to Win the US Open/Championships 5 Consecutive Times, Tied with Sampras for most Wimbledon titles in the Open Era, Tied with Sampras and Connors for most US Open titles in the Open Era, and Tied with Agassi and Djokovic for the Most Australian Open Titles of the Open Era.
Rafael Nadal: Lopsided Head-to-Head record vs. Federer, Owns a Winning Record against Everyone Currently (2014) in the Top 50 (!), Clay Court Winning Streak, Overall Clay Excellence, First/Only Player to Ever Win a Grand Slam 8 Times, Most French Open/Championships Titles of Any Era, Olympic Gold in Singles for Career Golden Slam, and holding the Most Masters 1000 Titles (and counting).
Notable Records Neither Hold
Calendar Slams – Rod Laver Twice, Don Budge Once
Total Years Finished #1 – Pete Sampras 6 (Federer 5, Nadal 3)
On the numeric, consistency and longevity side of things, Federer seems to be the GOAT. The head-to-head numbers suggest Rafa is betterer. It comes down to how one weights these categories. Of course, either of them could make this easier by winning more than 17 majors before retiring. If Federer adds to his haul and Rafa stays near 13, Federer could bolster his claim. If Roger stays at 17 and Rafa gets to 17 or more along with his head-to-head record vs. Federer, Rafa would take the debate.