At this moment my all time top 10 list would be:
(1) Novak Djokovic (most slams, most masters, has done the calendar slam twice)
(2) Rafael Nadal (second highest number of slams, king of clay, 29-30 h2h with GOAT, banana shot, greatest artisan)
(3) Roger Federer (streaks at US Open and Wimbledon, most Wimbledon titles, broke Sampras's record, most elegant player in history)
(4) Pete Sampras (Best serve in history, fourth most slams, slam dunk, did not lose a Wimbledon final)
(5) Rod Laver (11 slams, but he was the first man to do the calendar slam twice)
(6) Bjorn Borg (11 slams, made the highest streak in Wimbledon titles at his time, hybrid backhand)
(7) Andre Agassi (8 slams, won 5 slams after turning 30 years of age, great forehead, backhand and compact game, career slam)
(8) Jimmy Connors (most titles, the guy does not have a forehand)
(9) Ivan Lendl (8 slams, was a great player even though he didn't manage a Wimbledon title)
(10) John McEnroe (7 slams, 3 Wimbledon titles, graceful serve, cutest backhand ever, good hairstyle, flamboyance, charisma).
An honorable mention: Mats Wilander. He also won 7 slams and actually had a winning record with McEnroe in slams and had better longevity than him.