Not the "artwork", the album itself.
If we think of a work of art as necessarily being entire and of itself, we can't have albums that are part of a larger collection, because then the body of work entire becomes the work of art, like Van Goghs' Iris's or Dali. The work should be bereft of baggage like a backstory. One has to consider the work entirely on its own. There should be little commercial value at the time of production, because commercial interests corrupt the art as well as the artist. Ideally the artist should die or be otherwise unavailable to interpret the work, thus meaning it has to stand by itself.
I'll nominate The United States of America by The United States of America.
Like all good art, it challenges, entertains, amuses. It is well crafted and has complexity whilst remaining accessible. Most importantly, the band had the good grace to "die" by disbanding and each member heading off to relative obscurity, thus leaving the album pure and unsullied like a tiny diamond in a world of coal.
So we're not looking for "greatness" but the purity of the work of art.
