i don't really have a "favorite guitarist" - much as i don't have a "favorite movie". there have been, and are, so many good ones out there that, while their "stylings" may very greatly, it becomes too difficult to pick one over the other. they are either "very good" - or fall short of such praise, whether by millimeters or miles.
the late Frank Zappa's penchant for Edgar Varese-inspired, avant garde, compositions IMMEDIATELY walled him off from the greater body of the music-listening public. his "exile" was entirely self-imposed. Zappa appears to have had little interest in the trappings of popularity.
he was easily one of the most prolific artists of his time. the volume of his catalogue will blow you away. he was to recorded music as isaac asimov is to writing. anyway - i digress.
FZ authored some of the most blistering extended solos these ears have ever heard. prime examples are:
"don't you ever wash that thing?" - from the live recording "Roxy and Elsewhere".
"inca roads" - from the studio LP "One Size Fits All"
"carolina hardcore ecstasy" - from the live (in Austin, TX) recording "Bongo Fury"
"stinkfoot" - from the studio LP "Apostrophe"
if you are generally unfamiliar with this underrated "giant" of a guitarist - i highly recommend the guitar-heavy LPs "Overnight Sensation" and "Apostrophe" for starters.
some other lesser-known guitarists you may enjoy:
roy buchanan - "Loading Zone" LP. one of the greatest blues guitarists ever. the late roy flat tears it up on tunes like "green onions" and "done your daddy dirty".
steve morse of "the dixie dregs" - former guitar player magazine "guitar player of the year" winner
al dimeola - formerly of jazz-fusion greats "return to forever" - also a fromer GPM "guitar player of the year" winner. i recommend the trio of 70's efforts in my sigline.
dick dale - the godfather of "surf guitar" - no kidding, he'll blow you away.
rick white and bob watkins of "the screaming cheetah wheelies" - duelling electrics.... smokin'.
john mclaughlin of "the mahavishnu orchestra" - he and santana wail on "love, devotion, surrender" LP ('73). also check out "visions of the emerald beyond" LP ('74).
there are some really great guitarists out there. and many of them don't play in formats that are considered "radio friendly". check out as many as you can.