Well for me there's 3 groups I really listen to:
RPPR, obviously, because of the incredible level of professionalism and also the switching setups of players/GMs, which keeps it fresh.
RPGMP3, Hal's voice is like a little angel peeing in your ear. The groups are usually very synthed and the players work well together. There is a lot of "Out of game banter" but I like that sometimes!
Drunk N Ugly, thanks to RPPR I found a remote play group (which is how we mostly play, because we're allover Europe) that works really well and has very clever players.
I think that doing, recording and editting APs is a talent of its own. It should get its own category really...although it might get some fanRAGE going I suppose....
