Better, right. Ok, I've been listening to alot of Sabbath lately and it seems that Ronnie is pretty underrated as far as Sabbath goes. I've never had a conversation with somebody where Ozzy doesn't come up when Sabbath is mentioned. When you look at "Mob Rules" and "Heaven and Hell" It just seems that Ronnie fits. Mob Rules was my favorite Sabbath CD and Better than any Ozzy did vocals for. I'm not saying Ozzy is bad, but I liked his Solo work much better than with Sabbath. I just think Ronnie doesn't get enough credit for what he did with Sabbath. And the bullshit about Gene Simmons doing the Devils horns first, but that's not the point.
Well, I tried, if thats not good enough then eh..
Ozzy is always going to come up in any Black Sabbath conversation because the Ozzy-era was the longest, most prolific, and most influential era Black Sabbath had. Dio fits so well on the Dio-era albums because those songs were tailored to fit him. He wrote the words and helped in the writing and arranging of the music, things that Ozzy, for the most part, could not do. Ozzy can not play an instrument and Geezer wrote most of his lyrics. Geezer and Tony had to write with Ozzy in mind, but his own input was limited.
As far as some of the other responses in this thread, I'd say that Ozzy, in his prime, was not at all a terrible vocalist, quite the contrary, but his vocal range was very limited. Dio is far and away the better technical singer, but Ozzy is a better entertainer, for the most part, and that's what accounts for a lot of his longevity. Dio can sing his ass off but can't work a crowd as well as Ozzy and thus, does inspire as much devotion as Ozzy. One just needs to look at their respective solo careers to see that. Ozzy can put out mediocre and crappy albums and still draw huge amounts of fans. Dio does the same and is forced to play clubs. That's no knock against Dio's ability as a musician, but he's just not the entertainer that Ozzy is.
I like the Dio-era. I think that "Heaven & Hell" is one of Sabbath's all-time classics and the other Dio albums are great, too. However, there is clearly a difference in the Ozzy and post-Ozzy eras. Throughout much of the Ozzy-era, the band had that fuck-all, "I don't give a shit" aura about them and their music. They seemed more ominous and anti-social. With the Dio-era and beyond, the band became much more of a stream-lined heavy metal band. They were still dark, but didn't possess the same misanthrophic vibe of the early stuff.