Federer >>> Nadal, period.
The only thing that brings Nadal even close to Federer's dominance is clay courts. 6/10 of his grand slams have been on clay. Federer won EVERYWHERE but clay (well once of course, hence the career grand slam). If there weren't clay courts, Nadal would be mediocre at best.
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Americans are benevolently ignorant about Canada, while Canadians are malevolently well informed about Americans.