Well, no one is perfect. But imagine if you are able to construct a superhuman being with lethal serve, the ability to return powerful forehand, creativity to create beautiful volley, etc
Based on my reading online and off line, here's the combination of players (with emphasis on current players) at their best in each facet that will create the perfect male tennis player:
Pete Sampras has powerful and accurate serve. Most players will be very careful on their second serve but not Pistol Pete. Another player who is notable for his serve is Roger Federer. Unlike Sampras' speed, Federer's serve is unpredictable as you do not know where he's going to hit the ball.
It has to be Roger Federer. His forehand is almost perfect with the ability to hit from any angle with total precision. Another player with a violent forehand is Fernando Gonzalez. He has great pace and depth, with the ability to rip even from the corner.
Andre Agassi is well known for his backhand. He doesn't even mind to hit them using both hands. David Nalbandian, who uses both hands too, plays "strong two-hander up to the line" and is "safe and accurate".
Bjorn Borg has the most nimble and versatility feet. But in today's tennis, it has to be Rafael Nadal. He will sprint and hunt down a ball, hit it, turn, sprint again with so much commitment. This player basically runs after everything.
Ivan Lendl was never mentally tough but he uses his physical fitness to the max. He is fit, strong and almost robotic.
John McEnroe has such tremendous balance, he covered the net so well. In today's tennis, there are not good volleyers. Perhaps Novak Djokovic is a well enough volleyer who comes to the net well, and cover the court impressively.
Everyone has been talking about how smart Andy Murray is. He is a strategist, able to read the game and design points even though he lacks muscles to power the ball.
Well, there you go the players at their perfect best.
Sources: ESPN and The Straits Times.