Yeah, if there's one thing I can fault Dylan on, it's his lack of composition variety. A lot of his bootlegs sound pretty similar to his released tracks. Blonde on Blonde is his greatest achievement in both areas, lyrics and composition, but most of his albums are pretty standard music wise (I hate saying it). But to me, lyrics are the most striking attribute to popular music, so it takes the most importance. In that light, I don't think Dylan can be beat.
With both considered, I'd have to hand it to Lennon or Springsteen.