I have many man faves, but I'll just list a random few
Juan Carlos Ferrero - I like his game style. I know it bores some people, and many think that every baseliner plays the same, but I don't see it that way. I like how he moves so well, is so quick back and forth, etc etc. I like his cool demeanor on court, that doesn't give too much away (usually anyhow). I admire what he has had to overcome to be where he is now.
Fabrice Santoro - I just love watching him play. I don't know a lot about him personally, but he is such a clever, crafty little player that I can't help but smile at some of the shots he makes
He has such ugly, yet effective techniques hehe.
Mark Philippoussis - Despite all the surgeries, all the injuries, he has done his best to remain positive. Perspective will do that to you, but he has made the most of some crappy luck. Not to mention that IMO he can potentially do anything - when he is on his game is incredible. His serve goes without saying, his backhand is beautiful, he moves well for a guy his size (and his knees), his return of serve is good, etc etc.
Tommy Haas- purely based on his game. I was indifferent to him untill I saw him in Toronto this year live (i saw him in montreal last year too, but not a full set even), and he can do it all. While making it look easy.
Maybe i'll add more later