For my part, "Berlin" also remains one of my favorite (at least for the studio albums). It is this that I hear most willingly, usually, and in the end, I can almost hear as tubes: Lady Day, Caroline Says, How Do You Think It Feels, Oh Jim ...
"Berlin" tells the story of a couple, Jim and Caroline, through drugs, domestic violence, prostitution, masochism, child abuse and suicide. "Berlin" lays bare the despair of the lack of communication in love.
A concept album, in fact. And I love the concept albums, the ones that tell a story (any story for that matter). What I like about these concepts albums is the uniqueness that releases it; the fact that for an album, our mind is caught up in this music and this story and that it emerges more to the final mark. That is my definition of a good concept album. And "Berlin" is a prime. The studio album by Lou Reed that we must be absolutely at home.