Can't believe I hadn't seen this before. One I haven't seen mentioned is a personal favorite of mine, not an electric guitarist like most mentioned, although he did use amplification exquisitely IMHO, Michael Hedges. A bassist that he turned me on to, Michael Manring, is no slouch either.
I was surprised to see Frank Zappa and Dweezil Zappa mentioned only a few times, fantastic guitarists. Jimi Hendrix, Duane Allman, Dicky Betts,Jimmy Page, Jeff Beck, Alvin Lee, Eric Clapton, Jack Bruce, John Entwistle, Mark Knopfler, Buddy Guy, Robert Johnson, Stevie Ray Vaughn, Steve Vai, Jonny Lang, Ry Cooder, Leo Kottke, Al di Meola, Paco de Lucia, John McLaughlin, Justin Chancellor, Les Claypool, Carlos Santana, Jerry Garcia, Jorma Kaukonen, Jack Casady, Neal Schon, Joe Satriani and some others I'm not thinking of at the moment are among those are I like the most (my SF bay area roots showing in the last bunch
Just the other night ac500 came over to listen to my speakers and he used some Dream Theater as a demo, somehow I've never heard them before so will see about this John Petrucci guy now. I saw a video on the tv the other night with Sublime's new guitarist, Rome Ramirez, he's got some talent, too.