Joe Satriani!
I just think he's a true master guitarist. He combines the best of technical skill and speed with a true guitar feeling. It really is an extension of his body and you get the feeling he can make that thing make any sound he wants it to.
I realise this is more or less true for all these virtuosos, but I just think ol' Joe is a tiny step ahead of the competition.
Watch him play his excellent song "Satch Boogie" (from Surfing with the alien, excellent album by the way). He starts playing after a little guitar wanking for the crowd first.
It is awesome. Anyone who likes guitars must watch this. To the very end!
edit :
khfreek, I think I share some of your feelings regarding guitar virtuosos. I mean, speed and skill is not everything. I like it when you can hear that the guitarist really has a feeling for his instrument. There are so many guys who can play whatever really fast. For me personally, I put less and less value in that. I mean, if speed is all you like, you might as well just listen to Dragonforce ..
Okay, it's fast as **** knows, but I still don't like the sound of it that much.
(That video up there with the reverb playing probably sounds harder than it actually is, by the way. The reverb is playing half the notes! Nice tune, though.)