Ok here are some numbers then. In a three year span I saw Federer win 8 of 12 grand slams. He lost only 1 non-clay grand slam match, and the only reason he didn't win the French Open was because he had to deal with the best clay court player ever. At their peaks, Federer is who comes to mind when I think of the most dominant player ever and that's unlikely to change anytime soon.
All things being equal having the most ascetically pleasing game may be able to shade it but that's the thing they aren't equal.
Federer's first 5 slams were won against players outside the big 4 and when we're talking about sporting achievement in an individual sport both the achievements of Nadal and Djokovic are greater than his now not to talk about when they actually hang up their rackets.
Thing with Fed fans is when it looked like he'd win the most slams that was being used as the measure of his greatness over everyone else but when that came under threat by Djokovic and Nadal the conversation changed to what his game looks like, how gracious he is or whatever lame metric to judge an individual sport.
Federer is a great champion but he is not the greatest tennis player, that argument has been put to bed quite a while ago.
Look at how many times Djokoovic and Nadal have had to beat others in the big 4 in comparison to Federer, or look at the number of big titles he has compared to them. Honestly it's a terrible argument to call him the greatest point blank.