RF
It might be a cliche to say Roger Federer as the favorite tennis player, but I have many reasons why Roger is the best player and the player that has contribuited the most to the game.
First of course the quality of his game and his technique, that is something that is difficult to argue; other thing that make a good sportman is his attitude out of the courts and Roger is great whit it! One of the most important thing is that he is a gentleman when he loses! On top of all of this, recently Roger Federer, despite being 34 years old, has started to play chip and charge when he returns some second serves, an strategy that would consider forgotten for maybe almost of the players, he changed his racket a couple of years ago, he has done a lot already, but he continues improving.
Not to say anything about the records he holds... specially with everything related to Gran Slams!!!