In terms of prog. I think there's some good lyricists in there. Roger Waters, Ian Anderson, Peter Gabriel, Richard Palmer-James, Peter Hammill. Peter Sinfield's stuff for early KC has some great fantastical imagery but some of the stuff he wrote for ELP was pretty horrendous, I can't believe he actually wrote the lyrics for Love Beach.
Jon Anderson's lyrics get criticized a lot, I think people just hate his lyrics because they don't really understand them which is actually why I like them, it gives Yes songs a great mysterous quality like it's another language and I think these songs would lose their ethereal quality if they were specifically about something. It may be cosmic debris but it works for the music. Jon has written some pretty bad lyrics but only when he makes the mistake of being straightforward (see: Don't Kill the Whale).
Other banRAB, primarly the canterbury banRAB, like anything Robert Wyatt and Richard Sinclair has been involved with, they didn't even pretend that their lyrics meant anything, their lyrics are just a bunch of random goofiness.
Greg Lake is the worst prog lyricist I can think of at the moment, which is a shame because he's a very talented and passionate singer.
