75Joni Mitchell

Michael Putland/Getty ImagesThe strongest thing I did forJonias a producer onSong to a Seagull, from 1968, was keep everybody else off of that record. She was a folkie who had learned to play what they call an indicated arrangement, where you are like a band in the way you approach a chord and string the melody along. She was so new and fresh with how she approached it. It's the reason I fell in love with her music. She was a fantastic rhythm player and growing so fast. She had mastered the idea that she could tune the guitar any way she wanted, to get other inversions of the chords. I was doing that too, but she went further. I understood her joy in using bigger tools later jazz bands, orchestra. But the stuff she did that was basically her, like 1971'sBlue, was her strongest stuff. Match her andBob Dylanup as poets, and they are in the same ballpark. But she was a much more sophisticated musician. By David CrosbyKey Tracks:"I Had a King," "Nathan La Franeer," "Night in the City," "Coyote," "A Case of You"

76Robby Krieger

Michael Ochs Archives/Getty ImagesSchooled in flamenco and jazz, Robby Krieger pushed beyond rock at a time when most players were still bound to the blues. Inthe Doors, he had the improvisatory flair to follow Jim Morrison's wildest journeys, wrote some of their biggest hits ("Light My Fire"), and picked up the slack in their keyboard-drums-guitar lineup. "Not having a bass player... made me play more bass notes to fill out the bottom," he said. "Not having a rhythm player also made me play differently, to fill out the sound. I always felt like three players simultaneously."Key Tracks:"Riders on the Storm," "Roadhouse Blues"

77Willie Nelson

Paul Natkin/WireImageLike his conversational singing,Willie Nelson's guitar playing is deceptively laidback, playfully offbeat and instantly recognizable. Amazingly, Nelson has been playing the same Martin M-20 classical guitar, nicknamed Trigger, since 1969; it has defined his sound, a nylon-stabbing mix of country, blues and Django Reinhardt's gypsy jazz. Though the guitar now has a large gaping hole, Nelson still plays it nightly. "I have come to believe we were fated for each other," he said. "The two of us even look alike. We are both pretty battered and bruised."Key Tracks:"Whiskey River," "Night Life"