It should be pretty well known by now that Metallica's black album was really watered down in terms of song writing, but what I don't think gets said is that it was also really watered down production wise. It has this reputation as having this massive sound and partly why it sent Metallica's popularity through the stratosphere.... But to me the guitar tone is just really weak.... Master of Puppets, on the other hand, has one of the all time best metal guitar tones on any metal album, and I think that's part of the reason why retroactively that has become Metallica's most popular album years after them "making it." Their first three albums all have fantastic songwriting but Master of Puppets nailed the production.