As a person who's been playing guitar for over half his life, I'd like to weigh in.
My top picks:
Stevie Ray Vaughan - music just flowed out of this guy. If there was ever a reincarnation of Jimi, it was this guy. But to needinit, SRV didn't committ suicide, rather he died in a helicopter crash after doing a show with Eric Clapton and BB King.
I've been studying SRV's shit for over 10 years now and I still can't get it completely right.
Jimi Hendrix - This guy changed rock forever. Enough said.
Eddie Van Halen - Another genius where music just flows out of him. Watch him when he plays....he'll be pulling of the most incredible shit and he's smiling as if to say...."easy peasy...now watch THIS...!"
Joe Satriani - this guy is the godfather of modern shred. he may not be the fastest or the flashiest, but considering he taught: Kirk Hammett, Alex Skolnick and Steve Vai (used to be the fastest guitar player on the planet) I'd say he's got some skills. He's also probably the only instrumentalist who still has a massive following.
John Frusciante (red hot chili peppers) - he's not a fast player, he's not the most skilled. But melodically, this man is a genius.
The Edge - Like Mr. Frusicante, he's not a soloist or a shred master. BUT, the Edge is a genius in that he takes the guitar to a completely different level using effects. Just listen to With or Without You - most of the song is played with feedback and sounds beautiful. Genius.
Django Rrinhardt - two fingers. Enough said.
Slash - not the best technical player but damn this guy can rock out.