We had a similar topic with male vocalists, and a 'greatest guitarist ever' topic, but never one to just list guys with guitars that you think are awesome. Mine:

John Petrucci (Dream Theater, Liquid Tension Experiment, solo)

Michael Romeo (Symphony X)

Tony Iommi (Black Sabbath, solo)

David Gilmour (Pink Floyd, solo)

Frank Zappa (solo, Frank Zappa and the Mothers of Invention)

Adrian Smith (Iron Maiden, Bruce Dickinson)

Dave Murray (Iron Maiden)

Jimi Hendrix

Jimmy Page (The Yardbirds, Led Zeppelin)

Ritchie Blackmore (Deep Purple, Rainbow, Ritchie Blackmore's Night)

Alex Lifeson (Rush)

Stevie Ray Vaughn

Joe Satriani

Steve Vai (Frank Zappa, Alcatrazz, solo)