Well, I've only got Jam with the Band, but it's awesome. Yes, the songs are of poor quality (I refuse to say MIDI, since it's not correct

), but it's not notciable after a while, since you're likely to get completely absorbed by the song anyway. It's magical

It has over 30 songs, and most of them have 8 different instruments for each song, so really there are hundreds of things to play. There's also an expansion coming out in Japan (is it out already?) that almost doubles the song list, so if you have the means and the money, there's that too. Plus, Jam with the Band has 8-player single-cart multiplayer, which rawks.