It's a matter of taste, but I don't agree that the music itself is better in Rock Band. I've found some of their choices distinctly lacking. The representation of that music - the note charts, especially when the same song is available in both games, is generallly better though.
Yes, talking about the charting and such, choices and selection of music are always going to comedown to personal preference.
I never picked up a GH game after 3, but I will pop that back in every now and than just to play certain songs.
I, along with you, await the day when we can have our dream playlists available to us.