<S> Debrody Sir,
Ozzy, Ozzy. Dio was a great metal singer of course. But, Ozzy is King

Ozzy was rough in 1978 when Van Halen opened for Sabbath at the Philly Spectrum (VH's 1st tour).
Sabbath fired him. Career looked over till Sharon made her Dad take a chance, then OZZY was born

Dio was a 2nd string QB for Sabbath, as were many others, to include Deep Purple's ex lead Ian Gillan.
Heavan and Hell & Mob Rules had success, as did Live Evil.
None of the subsequent Sabbath's, Rainbow's, Dio's could match Ozzy's
popularity or success. A lot accredited to Randy Rhoads (rightly so), and Jake E. Lee and of course Zack.
Don't get me wrong. As I stated Dio was a great rocker. He did do some acting as well, I believe.
With that, he could have starred in a Travelocity commercial, played a Hobbit on LOTR, etc.

(He was quite short).
No doubt, Ozzy will be remembered longer and radio play of his songs will go on much longer than Dio's.
He's had much more impact on the industry than DIO could have ever had.

Oz