Steve Lukather - by far
All great answers. My vote is Jimmy Page but am also going to throw in Jack White, young but has some serious chops.
Was- Clapton with Hendrix right there of course.
Clapton is God was plastered all over London in the 60's for a reason.
Jeff beck by far.
Doug Pettibone. He palyed for Lucinda Williams for 8 years and now tours with Mary Ann Faithful. Great licks.
Surprised nobody has mentioned Trey Anastasio.
Jerry Garcia, no question.
A little late to the party, but here's my choices:
Hendrix - (from the past) gone too soon - unique sound, edgy, gritty & awesome
EVH - legendary: still rockin the rock-star lifestyle, but probably should slow it down a bit so he can stick around a while longer
Keith Richards - actually my #1 choice only because, well duh! He's the ultimate ROCK STAR from the ultimate ROCK BAND of all time. Oh, and much love to Mick Jagger - THE only rock band front man spanning 5+ decades and still bringing the moves on stage. Glimmer Twins
Prince - his purple highness, a true original, eccentric and nothing compares to his early funk-a-delic purple reign era tunes
Slash - really wish GNR didn't dissolve so early, but his other music is good too
Flea - representing the bass guitar department. No one else comes close to RHCP
Dave Grohl - not so much for guitar playing as all around musicianship. Drums, guitar, vocals - killer screams, song writing and magnificent concert performances. Also not a bad documentary film maker - check out Sound City Movie
Carlos Santana RULES...saw and filmed LIVE at SOLEDAD STATE PRISON... http://www.santana.com/Carlos-Jamming-With-Players/B/