Boy, am I late to this thread....
Those that would get a ten:
Heaven and Hell- Ronnie James Dio was and ultimately is, the only singer who could follow immediately after Ozzy in Black Sabbath. This album was monumental in that it made the public take the band serious after many years of drug hazed haphazardness... wow, say that three times fast! Anyhow, I love DIO, the man, the band, Rainbow, Sabbath.... not much into Elf, but hey, can win 'em all...
Vol. 4- I think the band was at their pinnacle right here. The heavy songs are really heavy, the ballad is one of the most sombre, innocent moments in metal. I feel the honesty in Ozzy's voice and the keys, mellotrons and whatnot are just kickfuckingass!