RE Heaven and Hell. I'm ashamed to admit this, but for 25 years I was an "If there's no Ozzy, it's not Black Sabbath" guy. I only considered the first 8 albums to be "Black Sabbath". That's no exageration.
Then a few years back, I listened to Heaven and Hell for the first time. Yes, that recently. I was absolutely blown away by how good it was, and for the first time, I could see that it truly was this album and Dio being the perfect Ozzy replacement that largely kept Black Sabbath relevant during the 1980s and into the '90s. It's really solid album.