I'm sorry, Mr. Perrotta.
There IS debate as to whether Roger Federer is the greatest player of all time. You don't get to cop out by saying "well, you can't compare players of different eras". You CAN say Federer played against inferior opposition for most of his career and never won the French when he had to get past Nadal.
You CAN say Sampras, or Agassi, or McEnroe, or Conners, or Borg, or even Laver and some guys I've never heard of were better because they may not have been as dominating, but they proved it against opposition that was as good as they were.
Top 10? At this point, yes. But I vehemently object to anyone who suggests there's no debate that Federer is the greatest player of all time.