Many fans refer Federer as the "GOAT" - The Greatest Of All Time. It includes ALL time - past, present and the future. They don't say Federer is the greatest to date. Even that term is extremely wrong as we can't possibly compare eras. We have no way of knowing how Federer would have fared against Sampras on grass and hard. But we do know he wasn't able to beat Nadal from 2008 to 2013 in a Major and that's a fact.
So yes, I absolutely disagree with the term 'greatest' and I have already given my reasons not once but twice. For the similar reason, Sampras also wasn't the greatest. He was the most successful until Federer showed up.
I did forget the 1995 loss but the % still doesn't go as high up as either Federer or Nadal which is more than 29%. And neither Lendl (8 Majors) nor Guga (3 RGs) fall into the same category as Sampras, Federer and Nadal, so the point is not even valid. Even Nadal doesn't fall into the same category as Federer and Sampras, because Nadal not only doesn't have 14 or more Slams, but also, he doesn't have the No. 1 ranking for record period of time or even close to it.
Sampras' record of 14 Majors and 6 straight years at No. 1 was the target Federer was chasing, not the other way around. I don't know how much either would have achieved had the eras been switched. And while Federer does have the most weeks at No. 1 than Sampras, Sampras' 6 straight years at No. 1 is another matter. It's much harder to achieve and Federer was toppled by Nadal, who also had Federer's number. It's not like Federer was injured and couldn't compete.
And I can give you 5 great claycourters from the 90s and I ask you to give me 5 names from Federer's decade who had won RGs. Granted, Federer made the RG finals a number of times, but that's all the more reason why he should have won at least 1 RG off of Nadal, as the chances were much greater for him to win at least one. But the reality is, he didn't. He won it after Soderling took Nadal out. I seriously doubt if he would have made the final a few times at RG in the 90s, but feel free to disagree because I know you will.