I'd add a couple more to your total context list Lamont: Revolutionary and Emotion. I feel Hendrix was the most revolutionary force in the evolution of eletric guitar. As for emotion, technical masters like Vai and Satriani can lack the punch of gut wrenching and passionate solos. David Gilmore, technically very weak, has some of the most emotional and impactful solos in music history. Who's better? who's to judge? Good debate tho.It can be unfair to judge past musicans against current ones particularly over long periods of time. Each generation builds off of and improves over the past. In 1967 when hendrix recorded my favorite solo on the Dylan cover "All Along the Watchtower" the Monkeys were topping the charts and i believe Sgt. Pepper by the Beetles hadn't been released. This month Hendrix is on the cover of Guitar World and Guitar Techniques Magazines and I believe Rolling Stone too 35 years after his death. I had a much more difficult time learning Hendrix and Stevie Ray Vaugh than I did learning Vai and Satriani or even Bach. With Vai and Satriani I could learn it straight off tab sheet music without listening to the song and it'd be damn close. I needed the music for Hendrix and SRV. How you strike a note is just as important as when, where, or how fast.
No one mentioned Chet Atkins
Here's a few more to add to your Great but Under-rated list. Marc BonillaSteve stevens (you gotta hear the instrumental CDs he did with Terry bozzio and Tony Levin)Jim Thomas (The Mermen)Mark Reale (Riot)Masayoshi Takanaka (Sadistic Mika Band, and Yellow Magic Orchestra)Danny GattonLaMont