So what is the bestest metal album? Sabotage? Iron Maiden? Back in Black?
Depends on how you define 'metal.' By your albums there I'll say best 'heavy rock' album is really the issue.
In that case I would say volume 4 for me!
Sabbath were one the first bands 'metal' was used to describe, Maiden clearly metal, AC/DC the only one you could possibly say are rock.

