The real musicians are good to have in Guitar Hero and it wins by that and the drumset but Rock Band wins by setlist and online gameplay.

Rock Band: Online gameplay with drums, guitar, bass, vocals and band
Guitar Hero World Tour: online with drums, guitar, bass, band and no vocals

GHWT vocals are a bit harder than Rock Band's vocals.
GHWT drums expect you to activate star power by hitting the blue and yellow drums but the twist is that you have to hit them at a proper time so you won't break a combo
Rock Band drums gives you a little drum free****mode before you go into Overdrive

GHWT has a pretty cheesy pro-faceoff because you play against someone of another difficulty so it's not very fair if you play in expert and the opposing player plays easy, medium or hard.

Rock Band 2 wins.