This is a loaded question on a couple different levels:
1. I am 30, and I am sure that puts me in the bottom 1/3 of active members where age is the factor. A lot of the FOG's here are well into there, well to be nice, late 40's. Hence all the old bands getting the nod. No one can argue against the Beatles, Stones, Floyd, Zep, Hendrix.... These groups of people defined the genre.
2. "The Best band of all time" isn't very well defined. Musically, longevity, album sales, sounds the best live and in the studio, influenced the most social change, or just personal favorite?
I am going going to say U2. U2 have prooven themselves musically, lyrically, by longevity, album sales, live concerts, socially viable, and my personal favorite. In addition to this, they continue to change the way they sound, without changing their sound. Let face it, when you hear The Edge play guitar, there is no doubt as to who is wailing out those beautiful sounds. You all can banter over the old bands, but in my mind, this band has everything and then some.
Emo