Best Heavy Metal Band of all time. (Do people still listen to metal?)

Led Zeppelin certainly inspired heavy metal, but were not a metal band themselves. What they did was light years beyond 'mere' heavy metal. Probably the purest and most innovative rock and roll band ever. So move to strike Led Zep from the list, AC/DC and Rush too.

Metal: Black Sabbath, Deep Purple, Iron Maiden, Metallica, Scorpions