You can't throw a brick in this town without hitting a great guitarist... but you should try. So what if you hit one or two?
It's really a stupid question, there are thousands of brilliant guitarists, and many you can't compare with one another because they play different styles.
Had a whole summer listening to Hendrix when beach bumming and surfing at Bell's beach in Oz when about 18 or so - not sure if he is the best, but brings back lots of memories!
Others:
Chet Atkins - My Dad listed to him all the time
Others:
Stevie Ray Vaughn - favorite of a buddy of mine who later committed suicide (memories again)
and Carlos Santana (Supernatural - listen to frequently. Best in a different way?)
Eric Clapton is up there - more the overall songs I like rather than the guitar work itself.