I have thought about this question a lot. For me, these are some of the most key criteria:
- Innovation - did they take the instrument and its capabilities further or just mostly copy others before them?
- Diversity of style - one trick ponies (just blues, just shred, just country, etc.) could be considered the greatest in a genre but not of all time IMHO.
- Output - were they able to have some consistent, sustained success over several years or were they one-or-two hit wonders? Duly noting - that some are the victims of circumstances that caused short careers - like SRV and Buddy Holly.
- Influence on others - this is a big factor IMHO because other guitarists tend to be inspired by the best players, like we are naturally drawn to the best in other areas like sports, other hobbies, etc.
- Songwriting/musicianship - after all, what good is a great guitar player outside of the context of good songs and rich, interesting music? And the more directly involved a guitarist is in the creation of great music, the more I consider that person "great".
- Chops/groove/feel - honestly, I give this one less weight because there are tons of great guitarists and the differences tend to be in the margins. That said, my pick for #1 probably spent thousands of hours jamming with his drummer brother.
- Regarded by other pros - I put a lot of weight on who the pros say are the "greatest" because it takes a great player to know a great player. I remember hearing that Clapton and the other blues players that shared the stage said that SRV was in a different league during the final Alpine Valley gig that he did right before he got on that helicopter and tragically passed. They were almost intimidated by him because he was so good at that point.
Based on my critieria, here is how my top FIVE (yeah, I know Mt. Rushmore only has four but I can't resist) came out:
5. Jimi Hendrix (the most legendary)
4. Jimmy Page (the most influential)
3. Joe Satriani (the most diverse who can play just about everything.. Sammy Hagar called Joe the best guitarist he's every played music with. Steve Vai is great at what he does but have you ever heard him try to play improvised blues? Plus Joe was Steve's teacher)
2. Stevie Ray Vaughan (otherworldly skill and feel)
1. Eddie Van Halen - his innovation was so ahead of its time - not just in technique but gear, his influence on others is unparalleled (anecdotal but I can list off a hundred or more players who started playing guitar because of him), the songs are great, lots of great output, the songwriting is at times magical, his feel was incredible, and he's regarded by many pros as "King Edward"
A personal favorite who is HUGELY underrated as a guitarist and overall musician: Rik Emmett (the guy can play rock, jazz, blues, classical, and just about everything else, he knows music theory almost as well as anyone (except maybe Pat Metheny), has written some of the best rock songs ever, and has been praised by Steve Perry for his vocal range - on Never Surrender he hits a high E note)...
