Well, I'll name a few favorites, then I'm going to list one who's been influential as a teacher, but he's not a favorite.
1] Guy Clark - He's probably the best conversational-type songwriter I've ever seen or heard. He's a great storyteller in his lyrics and they are seamless. He doesn't sacrifice clarity for a rhyme or prosody, but achieves them still.
2] Willie Nelson - He recognizes symbols and meaning in the most ordinary and simple things such as in "Hello Walls":
"Hello window, well I see that you're still here.
Aren't you lonely since our darling disappeared?
Well, look here, is that a teardrop in the corner of your pane?
Now, don't you try to tell me that it's rain"
3] Townes Van Zandt - He was, more than any other lyricist, a poet who successfully adapted his craft to songwriting. His song stuctures draw from sonnets, quatrains, etc. He may have been the most literate writer of recent times.
4] Joni Mitchell - Like Van Zandt she approaches songwriting with the eye of the poet, but she actually bends the music structure to fit her lyrics, using many elements of jazz.
There are dozens of others like John Prine, Tom Waits, Gordon Lightfoot, Eric Anderson, Steve Goodman, Kris Kristofferson, et.al.
A lyricist I've learned a lot from, but am not a great fan of was Ira Gershwin. He had lyric writing down to a science and was meticulous in crafting lyrics, abiding by syllable counts to match composers' work and not cutting himself any slack by using filler syllables or non-sensical words.
