Their fascinating rivalry is also considered the G.O.A.T! They are the only pair in men's tennis to have finished 6 consecutive years as the top two.
I personally believe Federer to be the better player. And I propose to manipulate the stats to validate my case. This is also a good reason why stats should not be unquestioningly believed.
Splitting into court types the Federer -Nadal records show 4-3 on hard courts, 2-1 on grass, and 2-10 on clay. So one could argue that Federer is the better player on 2 of 3 surfaces.
But there's more to this. The 2 being the top ranked players for the last 6 years, would invariably be seeded to meet in the finals. If more meetings haven't happened between the 2, it's because one of them fell off before reaching the summit clash. This has been Nadal more often. Federer has been generally more consistent in reaching the finals than Nadal.
While Rafa has been the undisputed master on clay (over the decade), Roger has also been pretty consistent in reaching the finals of a good chunk of the clay-court tournaments the two participated in. This has led to >50% of their clashes being played out on clay, though going by number of tournaments this should have been less than 25%.
What this could mean is that while Federer was the 2nd best player on clay, Nadal was not the number 2 on grass or hard courts. Though he has been showing more consistency on all surfaces in the last couple of years.
I immensely like both the players. Roger for his graceful movement, effortless artistry and panache. Rafa for his tenacity, magnanimity in victory & defeat and humility. Also for being left handed;) And both for their talent, competitiveness, sportsmanship and excellence.
But I am wary of stats. And 6-sigma.