The Greatest Rock Band Ever - was the Beatles. There are artists whose music we might enjoy more, there are artists who even had greater commercial success by certain measures, but the Beatles were the all time greatest because they changed the way everyone else was writing and performing music around them.
Agree or disagree? If you disagree be prepared to make a good argument (oh who are we kidding - just go ahead and make a lame argument to the contrary....Dude, like the Beatles songs are all SO stupid, and I think John Lennon acted queer, and like, Guns and Roses ROCK way harder, man....")
Oh, and make your nominations for The Greatest [Whatever] Ever too, so we can debate the merits, or just nod our heads in simple agreement.