Best band can cover so many things.
Most popular ? Most popular alive ? Most popular dead ? Most records sold ? Most songs produced ? Most hits ? Most gold records or albums ? Most platinum records or albums ? Most attendance at a single show ? Most attendance during a tour ? Most money earned ? Best live performance ?
I lean towards the Rolling Stones. Played in 6 decades so far. Mozart performed in 2 or 3 decades and hundreds of years later people still listen to him. I suspect in the future the Rolling Stones will be listened to for a long, long time.
LTG : )