OK so we've all had this argument and its all over the internet. Im going to give my opinion and then u give yours. Well after playing both of them I have to say I prefer Guitar Hero for solo play. The guitar gameplay is ten times better then that of Rockband with both fun and difficulty. But as for playing at a party I have to say Rockband is better. The vocals I have to say are really really fun and the scoring system is easier on Rockband as in Guitar Hero to get over 90% on Medium is a great feat as they mark you per word instead of per line which Rockband does. As for a setlist Rockband has got a bigger setlist and the songs on it are good and well known. But I have to say I prefer the quality of Guitar Heros songs as the solos are better and the songs are the greats instead of the well known such as the Tool gig, Crazy Train, Satch Boogie and Pull Me Under and it has some really good songs along with it such as Scream Aim Fire, B.Y.O.B and Dammit. With the addition of open notes in GH I think for Bass its better. And the drum layout for GH is also better as for how the two of these play Ill leave ye to comment.
As for Game design GH all the way. I dislike the RB look and the charachters from GH are few and well known throughout the series. Like everyone can remember Axel Steel, Clive Winston and Judy Nails. But RB charachters just look weird and generic. Also the whole solo scoring doesnt add anything extra to the gameplay and with GH at the end u can check the percentage for each section instead of just overall.
Overall I prefer Guitar Hero when it comes to Guitar but for fun as a group I say Rockband. Smooth Criminal is the funnest song I have ever sang and no Passty there is no limit to the fun you can have by holding your crotch and sayin Bow!!!.