I'm with you on Bob dylan et al above. Some additions; Bruce Cockburn, Van Morrison, Joni Mitchell,Lyle Lovett, Ani Difranco, and Neil Young.
I think it's the imagery that these people use, their ability to make me "see' their story, "feel" their words that I appreciate so much, combined with such a great melodic/groove sense.
What I find fascinating is their ability to write batches of songs at a time, say, for a particular album. I often think this is where you get some stinkers; the difference is people like me don't have the luxury of massive amounts of studio time to record the really crappy stuff, so there is a silver lining to limited opportunity.
What I find happens to me is that I get many parts of many songs, but seldom the whole thing at once. The trick I think is to go back to these songs regularly to try to finish them, but more often I keep going on, producing more partially formed ones.