I would say Motorhead
Without a doubt....DEF LEPPARD!
I disagree, LG, Def Leppard can jam with the best of them. So can Van Halen. Saxon, Priest, and Maiden are a bit heavier, but not so much so that they out class Def Leppard. Def Leppard is more ballad driven than Priest or Maiden, but they can still jam heavy metal style.
I can pick more, but what most people remember from Def Leppard are the Popular rock ballads that the radio played .