Some great inclusions for sure. I'd add some well known stuff:
Running Wild - Death or Glory
Virgin Steele - The Marriage of Heaven and Hell Part Two
Lost Horizon - A Flame to the Ground Beneath
Labyrinth - Return to Heaven Denied
Stratovarius - Visions
Angra - Holy Land
Sorry, but YJM's Trilogy is a snoozefest. I was a monster Yngwie fan when that came out. I wanted to like it but just couldn't. Still can't. I think the best Gamma Ray's record is Land of the Free, although Somewhere isn't far behind.
Pretty sure my #1 power metal album is Fairyland's Score to a New Beginning (2009). It's completely keyboard-dominated -- the keyboardist/main-songwriter lost or fired the entire band and did their third with some hired hands -- and the results were impossibly cheesy but also irresistibly powerful and catchy (for me anyway).