I would say......Rock Band 2. Rock Band 2 has a very robust selection of songs ranging from classic rock anthems such as Pinball Wizard and Let There Be Rock all the way to newer bands like Paramore and AFI. The animations for Rock Band are far superior to Guitar Hero's and the game really makes you want to jump up and start doing scissor kicks whilst wield your plastic fisher price axe of terror in your hands... Rock Band's character models look much better than Guitar Hero's and the wide variety of features and clothing are a nice touch. Unlike Guitar Hero, Rock Band has warehouses full of DLC, and a nice amount of them are free. The ability to download the songs from the Original Rock Band was another amazing feature as well. All in all, Rock Band has everything you would want in a music game....and much more, and will keep you coming back for more, again and again....
It almost has everything but I still feel much more satisfaction beating guitar hero because it is harder.
Which Guitar Hero was this? Guitar Hero World Tour was a disappointment in terms of difficulty, and Rock Band 2 was harder than GHWT....