In no particular order:
Iron Maiden - Seventh Son of a Seventh Son
Iron Maiden - Powerslave
Judas Priest - Painkiller
Nightwish - Century Child
Queensryche - Operation: Mindcrime
Led Zeppelin - IV
Helloween - Keeper of the Seven Keys part 2
Ayreon - Universal Migrator
Avantasia - The Mystery of Time
and too many others to list. I couldn't even pick a 10th album, since I would be leaving out so many great albums from bands and artists I love.
Some great choices. Was contemplating some Maiden for my list (Piece of Mind probably... or Brave New World), just not enough space though.
What made you go for The Mystery of Time over all the other Avantasia albums?