Metallica - they wrote good thrash metal back in the day I suppose, but apart from that they have never been innovative or exciting to me. I do like to listen to them occasionally.
Aerosmith - great band (apart from some of their newer stuff. Who the hell is this Desmond Child character anyway?!?) but they have NEVER been innovative. Joe Perry is an underrated guitarist though in my opinion - he has a great ear for melody. But again, I don't think they deserve to be the best band.
Queen - I wouldn't have voted for them, but of these three I would say they definately deserve it. Brian May invented the whole orchestrated guitars thing, Freddie was the greatest frontman EVER, all the members wrote hit songs, and they changed their sound dramatically, seeing as how they weren't afraid to have fun with their music along with the more serious music. I would definately say Queen deserve out of these three.