ehhh both guys have been playing competitive tennis their entire lives. Nadal has also taken a lot more time off than Federer. Let's not forget that Fed defended his #1 ranking for almost 6 years straight, something only matched in the modern era by Pete Sampras. For context, Fed has held the #1 ranking for 302 total weeks in his career... while Nadal has only held #1 ranking for 119 total weeks. While some people like to just point at majors as the only way to rank players, in a sport like Tennis, where the top players compete against one another all year long, not just at Majors, it's ridiculous to disregard consistency. Tennis isn't like Golf, where you can just show up and win Majors, and take the #1 ranking. In Tennis, there are dozens of highly competitive events throughout the season that are must wins for anyone who wants to achieve a high ranking. For example, the event I always attend in March, the BNP Paribas Open at Indian Wells, has every one of the top 20 players in the world attending on both the Men's and Women's side.
Have a look at that entry list. The same exact players that you'll find at any of the Majors. The points rewarded for the tournament are also on par with the Majors.
I think the 300+ weeks and all them WTF tourney wins he's had is cancelled out by being dominated by someone else who is not even 5 yrs younger than him. Fed has lost in 2006 to him while in his prime.
I'm not saying Fed ain't still the GOAT, because I think he is. Nadal has a few more slams to win (including today's) to officially overtake him. Imagine if Nadal gets a triple career slam... He'll have his double if he wins today. But he still has a long way to go. Federer got his career slam when Nadal got knocked out by someone else at the French Open. So there are no asterisks, you can only beat who's in front of you.