I'm surprised how much overlap in the song choices there is between the Rock Band setlist and the GH:WT setlist. That said, in terms of guitar anyhow, I find myself liking Rock Band more than GH:WT more and more as time goes on. The songs only on WT are pretty awesome, but seeing how the note charts differ between RB and WTis kind of a turn-off, and I feel like the RB note charts are more correct (see: Everlong).
Plus the drums for WT took a lot of getting used to, not only because the notes look pretty different and all, but also because there's a much shorter grace period for note hits.