Rock band 2. People are saying it's just like Rock Band 1. Well, I'd have to agree and say Rock Band 1 is better than World Tour aswell.
I don't really care for the GH drum kit, probably because I already loved the RB kit, but I found drumming extremely more fun on RB 1 / 2.
Also, I absolutely HATE the art style of GH. I have since GH 1. And it's gotten worse. I've also hated the way the notes/highway have looked since GH 3.
On the other hand, I love the way Rock Band looks, but these are massive opinions, which is what you are looking for, I guess.
RB2plz.