For me it's Iommi,without him there's none of the great players (Hammett,Dimebag,Rhoads etc etc) doing their thing. My thoughts on Blackmore being heavy well,yes he was .Not as heavy as Zakk or Dimebag but they were voted loudest band by the Guinness book of world records. Purple along with Zep and Sabbath in the early 70's were looked up to as the" Heavy" bands around before the next wave came in such as Kiss,Aerosmith and a host of others in the 70's. But let's face it they all rock so let's enjoy it.