Federer? Laver? Borg? Sampras? Many people have declared the "Greatest Tennis Player of All-Time." In my opinion, you cannot compare players from different Eras. (I have violated this, but now that I really come to think about it, so instead of saying Federer is the best, or Laver is the greatest, I see that it's very difficult to compare. I will put forth a few arguments from my point of view.
Let's start with the the tools. The tennis racket evolved a from wood to the modern racket precisely because the modern one is better. What would Federer be like with a wooden racket? What would Laver be like with the modern racket?
It's like comparing a cook with a good spatula with a cook with a broken spatula.
Second, the opponents. There was no Nadal in Laver's time nor a Rosewall in Federer's time. We can't tell how a Nadal-Laver or a Rosewall-Federer match would have fared.
This is something that only concerns Laver, but in some of his career, good players wouldn't play in Melbourne for the Australian Open.
This might have changed the results of the tournament.
In conclusion, I say that we should not make a list of all-time greats, but say that there are many masters of tennis.