Anyway, so far I've downloaded 12 songs from RBN, and personally I love them all. Some of them were pretty safe bets (i.e. Even Rats, Push Push (Lady Lightning), but some of them I bought before even having heard the song.
On guitar, my favorites out of the ones I have are: Push Push (Lady Lightning), Code Monkey, Collapsing, and Drunken Lullabies (Live).
On drums, my favorite is: The Girl at the Video Game Store.
On vocals, my favorites would be: The Jonathan Coulton songs (Code Monkey, Creepy Doll, The Future Soon, and Ikea), and The Girl at the Video Game Store.
I haven't really played anything on bass yet.
But out of the 12 songs I've downloaded, I don't dislike a single one.