I was not going to answer, because as a lyricist-aficionado there'd be too many to pick from. Bob Dylan, Leonard Cohen and Joni Mitchell have already been mentioned early in the thread. Like young Dylan, I'm a resident of "Baja Canada" and wonder if how far up into the 40s latitude-wise one has to be to write great lyrics!
Any such discussion, even if it's about favorites, has to tip their hat to Bob Dylan. Song lyrics pre-Dylan and song lyrics post-Dylan are operating in two different worlds. Cohen (who always praised Dylan) and Mitchell (who liked to tweak Dylan's reputation and boost her own sometimes) both have acknowledged that. What Dylan did is take some things that poets had already been doing and brought them back to musical contexts. In doing so he totally expanded things that songwriters could do.
Then I figured it's an excuse to toot my own, and my Parlando Project's horn. The Project takes other people's words and performs them with music. Here's a lyric Dylan could have written, but didn't because a non-songwriter Jean Toomer wrote it in the 1920s. I set it to music and performed that combination. See if you don't think of Dylan's
"Visions of Johanna" when you hear this lyric. The following link will open up a new tab and play my perfromance.
Her Lips are Copper Wire
For me, coming upon Toomer's poem in the middle of his book
Cane was a jaw-dropping moment. A great lyric. As to the performance, Greil Marcus seemed to like it a bit.