So after working through an intensive, several month long Black Sabbath kick, I’ve more fully investigated the range of Dio and have decided a couple things. First off, the best albums from the main Dio bands:

Dio - Holy Diver
Black Sabbath - Heaven and Hell
Rainbow - Rising

Second, Im still unsure of which is the crowning Dio achievement, but Im leaning towards Holy Diver followed very closely, however, by a lengthy interview on the deluxe remaster (of Holy Diver) that rivals the entertainment value of the album itself.