Rory Gallagher, Frank Marino, Robin Trower, Jimmy Page
These masters belong in the top 20, and can frankly mop up the floor with most guitarists. But, more importantly, they have consistently each turned out reams of meaningful music, not just flash. Furthermore, they always experimented in subltle ways too with new ways to approach and express things. Each of these guys had integrity, a truckload of firepower, and often invented somewhat new musical forms of their own. They're not alone either, I'd like to see Gary Moore, Ronnie Montrose, Michael Schenker,Paul Chapman, Laurence Archer, and others get more recognition. I'm sick of hearing about Clapton or Van Halen all the time, they're good too, but have received way too much recognition.