If both games were launched tomorrow with all the option that have been announced, wich one would you buy and what would the other game have to get your money?
Personally, i would buy Guitar Hero: WT, mainly because of the songs and the customs song, what Rock Band would have is:
Compatibility with Guitar Hero's Guitars
More song that i like (Not DLC)
Something similar to the custom songs (this is just a bonus)
**I meant buy, not but.