the best indication of guitar greatness is what can be done on an acoustic, without the need for dubbing, fancy effects units, whammy bars and things you can only do on an electric e.g. double tapping. For true genius the top players in my book are

Leo Kottke - just check out the 'armadillo' album or 'Greenhouse'
Adrian Legg - sounds like 3 players.
Paco de Lucia - his finger style playing is faster than most shredders sweeping.
Martin Taylor - the way MT can play fast walking basslines, chords and melody lines simultaneously is something else
Tommy Emmanuel - TE is an Australian guy who does a lot of live solo shows. check him out and be gobsmacked. He will inspire or make you give up.

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