damn, that's a tough one. ok, i have my top 5, but don't ask me about the order.
joe satriani
john petrucci
criss oliva (incredibly underrated)
al pitrelli (love his unique vibrato on bended notes)
greg howe (listen to his stuff, the man's insane!!!)
but once again, these are my top favorites, and not necessarily my opinion on best ever guitar players.
and to push this to top ten, i'd also add:
al pitrelli (love his unique vibrato on bended notes)
alex lifeson
adrian smith (my favorite iron maiden axeman in every way)
eric johnson (he's even more incredible to watch. how can he play so fast but so clean?)
tony iommi
i forgot to add the guitar player from Pagan's Mind, Jorn Viggo Lofstad. he's got such an awesome tone and is an incredible progressive player. definitely one of my guitar players today and one of my favorite bands. i highly recommend them.
too many...but in no particular order : John Petrucci, Joe Satriani, Steve Vai, Al Dimeola, Ioannis Annastassakis...in my opion....honorable mentions: Paul Gilbert, Goncalo Pereira, Eric Johnson, Paco Dilucia, Al Pitrelli, Greg Howe
Mine would be
1. John Mayer
2. John Frusciante
3. Neil Young
4. Eric Clapton
5. Jimi Hendrix.
a few others i wanna mention: Buddy Guy, SRV, Jeff Martin, Stephen Stills and Lenny Kravitz. I don't feel thats a list of the best but my favourites.