I guess you're asking because money is a concern, but Guitar Hero 3 is only $30 cheaper if you are starting from scratch and only buy the game and 1 guitar. Of course, then you are only another $50 from getting the drums and mic included in the special edition. If you can afford it, Rock Band is going to be better imo because of more downloadable songs (thanks to MTV license), the original GH developer, Harmonix, and the drums are just like the real instrument when you get to expert.
Also, you can use the mic and either play drums or guitar to play "co-op" by yourself. That's a nice feature.
However, if you buy Rock Band you might as well get the Guitar Hero 3 bundle as well because then you'll have 2 guitars, drums, a mic, and both games! That's $260, though, heh.
