I'll bite. METAL POST ON THE WAY
Jorn Lande (solo, ex-Masterplan, ex-Ark, ex-Beyond Twilight, guest in Avantasia and Ayreon) - This man just has an amazing voice. The ability to maintain range with a grit and cry is so powerful. Unfortunately, he's an ass.
King Diamond (ex-Merciful Fate) - Holy falsetto Batman! This man-beast scares the bloody Hell out of me. Haunting screams at an insane range combined with a black-metal like atmosphere (or actual black metal for Merciful Fate) will make Freddy Kreuger re-think who really should be stalking you in your dreams.
Hansi Kursch (Blind Guardian, Demons & Wizards, guest in several others) - My pick for favorite, most entertaining vocalist (inspired by Freddie Mercury). This man + voice dubbing = the most epic sounding tracks I've ever heard. I could listen to him scream "Nightfall" until the end of time.
Kai Hansen (Helloween, Iron Savior, Gamma Ray) - POWER. Just straight up POWER behind this man's voice. Blows your hair back anime style.
Tobias Sammet (Edguy, Avantasia) - So wonderfully melodic and one of the cleanest voices in power metal I'm aware of.
Rob Halford (Judas Priest) - I don't care how well known this man is. This is why:
YouTube - Judas Priest - All guns blazing Live 1991, Painkiller tour
[Sir] Russel Allen (Symphony X, guest in Ayreon) - Anger, power, prowess, and class. This God among prog-power men has it all.
Marko 'Marco' Hietala (Nightwish, Tarot) - No, not the CHICK from Nightwish, but their long haired bassist who also sings in a band Tarot. Wonderfully unique voice, a great deviation from most. His Phantom of the Opera live from Nightwish's last live album never ceases to send chills down my spine
Jari Mäenpää (ex-Ensiferum, Wintersun) - The man who got me into harsh vocals (along with Mikael Åkerfeldt of Opeth fame, who isn't on this list because he was previously mentioned). His epic song writing combined with a wonderful harsh/clean dichotomy keeps me coming back for more.