I strongly prefer Rock Band 2 to Guitar Hero World Tour. In terms of "non-quickplay" modes, Rock Band 2 retains the tour mode present in Rock Band 1 in which you earn fans, stars, etc. and progress from city to city unlocking new songs. From what I've read, the new Guitar Hero's "campaign" mode of sorts is not as cohesive.
Band play, in my opinion is also better in Rock Band 2 due to some strange design on the part of Guitar Hero. For example, it is difficult to tell when a bandmate is going to fail out of a song, and it only takes one band member to fail for the entire band to fail. Also, although this is purely subjective, I like the rock band 2 soundtrack much much more than guitar hero's and love the fact that dlc comes out so frequently for rock band.
Guitar Hero has its perks in terms of its song creation function (I'm not sure exactly how well it turned out, though), and some of its other features like the open notes for bassists, however, I give the edge to RB2.