Excellent:
This American Life
99% Invisible
Very good:
Planet Money
The Memory Palace [historical narratives]
The Moth
On the Media
Snap Judgement
Good:
Freakonomics
Radio Lab
Radio Diaries
Occasionally good:
The Truth [fictional radio dramas]
Criminal
Dan Carlin Hardcore History. It's not in often and when it is it can be a 21-hour series. The guy is brilliant and I could listen to him tell a story about the most boring man on the plant if he decided to.
Really good list! I'd move On The Media to Excellent, it's really cream of the crop. And I'd throw Skeptic's Guide to the Universe in there too, for anyone who likes science. If you like ancient history, add Dan Carlin's Hardcore History.
Agreed on On The Media. It's basically just meta-news, but stepping back and looking at the narratives being presented is really interesting. Their recent show about this history of political polling was fantastic.
Stephen West does an outstanding job of tracing the complete history of philosophy in the West and relating its ideas to modern thought and idioms, and uses humor effectively as well.