OK, there's 2 trains of thought, one is who shaped metal in the 80's and probably since I'm a guitar player who shaped it with guitar, or who was just the best metal / hard rock bands. I'm going to go with just the band angle
in no order:
Iron Maiden
Metallica
Queensryche (may seem an odd choice but they were progressive for their time, no one else did what they did)
Ozzy with Randy
GNR