Dio is a great singer...but in the last years he sounds like a bad copy from himself, the same melodies, the same tone, the same lyrics, the same stupid fans.
His success has fineshed in midles of the 80's due to the lack of inspiration in his songs. Because he is a more technical singer than Ozzy is, he never could accept the ruge success reached by Ozzy. It was cause of envy by Dio, that is always finding a way to underestimate Ozzy's work in his enterviews. What happens is that the Dio's fan were contaminated by this feeling of envy.
Ozzy does not have the same vocal quality that Dio has, but in othe aspects he's been much better, he writes better melodies, he has a more commertial tone, and is not necessary to talk about charism.
Each one has the desearved position in the Rock n' Roll history.
Dio is a great singer, OZZY IS THE KING!!!!

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Fabiano Negri - Singer