I used to think Rock Band was my favorite, until I got used to the notes in Guitar Hero, then I understood why GH was more popular than RB, Guitar Hero is...well, was Great until they put out Guitar Hero 5! There are some cool things about it, but for the most part, the music sucks compared to the other GH's and all those stupid challenges, like strum as much as you can, or keep a 4x multiplier as long as you can; they might would be okay if I owned and played every instrument, but I only play guitar so I can't even do all of them. Anyway, GH5 definitely sucks and Rock Band 2 has some really neat songs in it and I like it but seems like I'm just playing the same songs over and over again and never getting anywhere. I hope this helps.
PS-Don't waste your money on The Beatles unless you are just a die hard fan and can't help yourself. The music, although is true Beatles' music, well the songs are too short and very easy and boring to play. The track is an awful pastel light green color and the notes are pastel as well. I can't believe they would put something like that out I am glad I rented it before I bought it.