I don't have either yet. We played RB at a friend's house, and my son (7 years this week) wants it really badly. Looks like it'll be a Christmas gift (for Wii). I'm looking at
LEGO: Rock Band, to cut down on the songs with questionable lyrics. There's also
Band Hero, which is also supposed to be more family-friendly, but so far the RB version seems to be a better track list.