Roy Kahn era Kamelot!!! The Black Halo, Epica, Karma and Fourth Legacy albums specifically. Listen to the title track to Karma to get an idea. That's one of my favorites, but there so many great tunes on those albums. Also check out Roy's band Conception. He left Kamelot and sang in church for years, but is back with Conception and I really dig their new EP.
I LIVED for Rush, Queensryche, Fates Warning, and Dream Theater in the 80s/90s. So when I tell you to check out Kamelot... "listen to me now and hear me lay-duh!" Kamelot was who mended my broken heart that lingered for years after 'Ryche shit the bed. They were THAT good with Roy singing. Tommy sings well too, but the music isn't the same without Roy there. Kinda like Ryche without DeGarmo. Both bands had peaked already, but those departures sealed their fate. I do like LaTorre on vocals for Ryche though. He's better than Geoff Taint has been in two decades... and he can drum!
Marillion are another band that I've loved forever. Maybe they're mellower than you're into. They're like early (Peter Gabriel) Genesis meets Pink Floyd.
Have you heard the Warrior album from the 80s? It was killer then, and it's still killer. Shame that was it for them. "Fighting For The Earth" was the single that got video play. Perry McCarty (the vocalist) did an album with Steve's Stevens' Atomic Playboys after Warrior.
What about Tarja era Nightwish? Love em! What about Saga? Love em! There's more amazing prog or prog-ish stuff out there than you can even take in.
I just got obsessed with Devin Townsend Project... and haven't this obsessed with a band since Kamelot, and Queensryche, Fates Warning, and Rush before that. Check out DTP's Hyperdrive, Seventh Wave, Deadhead, and other great tunes from him to get an idea. Not high register per se, but got much else of what you stated.