Here in Spain they were arguably the biggest power metal band ever. Shirts with their art were very common - a tier below Maiden shirts, but putting up a respectable fight in popularity. They also filled some of the best venues - not stadiums, but the tier right below, the premium venues, which I think is a great achievement for such a niche genre.
When I was a kid I loved some of their classics like Mirror Mirror, but I wasn't as much into them as some of my entourage, as I preferred other styles of vocals. Recently however I've come to appreciate them again because Spotify suggested "Sacred Worlds" from the album Edge of Time. I love fully orchestrated metal - Metallica's S&M with the San Fran Symphonic or Nightwish's Once with the London Philarmonic - and "Sacred Worlds" is an absolute banger within this rare subgenre.