Band Hero or Rock Band?

[aggiefamily]

Santa wants to get the family one of these for Christmas. I don't know which is better or what would be easier for us to use.

My boys mainly listen to kids music (someone needs to make a game with kids only music!), a few pop songs and country songs.

Oh we have a Wii.

eta: are the guitar hero or rockband wii games interchangeable with both band hero and rock band? could I buy a rock band wii game and use it with the band hero hardware?

Pros or cons for either would be appreciated!