Well my top 3 are kinda generic in that they're so mainstream and perhaps overplayed, but I can't deny their influence on me...
*Billy Gibbons-master of pinch harmonics, and classic riffs/progressions
*SRV-perfect balance of tone, skill, and soul
*Jimi Hendrix-Red House...nuff said
And yeah, I concur with John Mayer's blues abilities. One would never know from his pop radio stuff. I've seen BB King 2 times, and he was good, but I think his excellent backup band was nearly better than him...still a good showman though. And someone also mentioned Kenny Wayne Shepherd, who I saw when he was first making a name for himself (for free no less!). That was a good show, but I never got around to buying his cd's.
One somewhat obscure player worthy of mention is Austin legend...
Joe Richardson
[FONT=Palatino Linotype]"Bust a nut!" - Dimebag
"Imagination is more important than knowledge." - Einstein[/FONT]