Right now "alive" i'd go with Warren Haynes, after that it's hard for me choose.

Some of my favs:

SRV
Duane Allman
Derek Trucks
Jimmy Page
Tommy Bolin
Billy Gibbons
Joe Sattriani
Hendrix

I really don't know where to begin,but I'll name a few that haven't been mentioned yet.

Frank Zappa
Alvin Lee
B.B King
Les Paul
Steve Miller
Joe Perry
Angus Young
Peter Frampton
Leslie West
Dickie Betts
Tony Iommi
Ted Nugent
Neil Young

BB, Les Paul and Dickie Betts. Doesn't get any better does it !!! Would love to hear them all with Stevie Ray playing also !!!!!!

Gawd! I wish I hadn't been so concentrated on the GOLF threads when this came up. Since I've played the instrument for many years - badly, compared to the "name" players - I have an opinion here.....
That opinion is - you CANNOT declare one guitarist "BEST"! There are too many categories and styles. BUT - having said that, everybody has their "best" for their taste - that I will not argue.
Allow me an example:

Mark Knopfler - probably one of the greatest 'technical' guitarists to walk this planet - but then, there's Eric Johnson from Texas. Mark plays that clean Dire Straights sound, whereas Johnson plays with effects and distortion - but he's a technical genius and most of his riffs are based in the classics. Go on You Tube and call up Cliffs Of Dover - watch the one where he has the British Navy shirt on - nuff said. I have incredible respect for both of them but I prefer Eric Johnson. He's not afraid to just put it out there.

Oh! And another -
Stevie Ray......There's tons of REALLY GOOD blues players out there but what makes Stevie unique is that he doesn't give you time to even breathe. By that I mean, so many blues players will throw a riff at you and then sit back for a few bars before they play the next riff. Not Stevie! He starts a solo and just keeps comin' at you - never a break - just a stream of consciousness - like it's just flowing from his imagination direct to his hands. And, yeah. I'm a BIG fan - so I'm biased - so sue me. Hehe! BB is a genius but he won't turn it up an let it sing, Albert King is a legend but I can't stand his 'bup-bup bup' choked-off picking technique...... I'll take Stevie for the raw energy - every day.

I guess what I'm saying is that ALL the guitarists in Roy's list are GREAT players ................ but, you can't call any one of them "the best" - just your favourite. There are too many variables in terms of styles and music genres.

JMHO
Cheers all
Tele

Great post and very true,,,, !!! All great in their own right. !!!!

Stevie,,,,,,,,,,,,,, my all time "Favorite" !!!!!!!!!!!!!!