The first person that springs to my mind is Federer, he's intelligent, nice, and blah blah. But then, giving a second thought, I think that he can quickly become quite boring. Second in line is of course Nadal, but he, on the other hand, doesn't seem very intelligent (and I repeat "seem"). Before he opens his mouth, he's attractive to me. So, I've erased Federer and Nadal. To make it short, after some thinking, I came to the conclusion that my favorite is Djokovic: he's smart, mature for his age, interesting, ambitious, ... On the long run, I think he's the best. To complete the list, I'm choosing Gonzales and Tipsarevic (based just on looks).

Celia, the Toronto event is well-attended, so book at least four to six months ahead if you want to get good seats for the quarters onwards. The event is well organized, the top players are usually there, and you'll enjoy the whole experience both inside and outside the center court.

Marija, if you think that Federer is boring, watch this:
http://www.youtube.com/watch?v=qNU8qTHH8xs&mode=related&search=

and read this:
http://www.tennis-x.com/story/2007-07-28/i.php

Nadal is quite bright despite his intensity. Here's another side to him, smiling and having fun in a match.
http://www.youtube.com/watch?v=VM3VZKm9A58&mode=related&search=

Another Perspective,
Video b/w Agassi and Federer was funny discussing haircuts.