I wouldn't consider Kiss to be heavy metal, although at the time they were gaining popularity they were getting all the right people up in arms about their image, which definitely had that heavy metal vibe. The music, though, just rock, and not all that good.
I spent a lot of time with King Diamond as well as a listener. I wouldn't call him "bad", but distinctive. I liked his storytelling dramatics for a good long time as a college student and a couple of years beyond. I've gone back to try to recapture some of that magic but I don't care for it any more.

James LaBrie I'll go along with. I can't stand listening to Dream Theater any more.