Quoted from Frippertron:
Guys, go on YouTube and listen to Keeper of the seven Keys part 1 by Helloween and tell me Michael Kiske isn't a beast. He isn't as popular as the others but WOW.
I voted for DIO, but you are absolute right. I saw Kiske oft enough (First time 1990, last time 2016) and in my opinion he was and still is the best!