New to the forum and flicking through a few days and found this topic and thought I would chip my tuppence worth in for what it's worth. I appreciate it is very subjective there are so many and it changes with my mood and whatever I'm listening too so firstly mentioned in despatches has got to be Jeff Beck, Jill Jackson and George Benson. However the three I always come back to are:
Frank Zappa - so underrated it's unbelievable, even if you don't like his music give it a listen just for his playing.
Paul Kossoff - just a sublime guitar player IMO.
Finally John Martyn what he did with a guitar was absolutely amazing, especially when he taped the pick up on his acoustic and used and ecoplex(?) In the 70s.