Obviously inspired by @PP_BOY_@lemmy.world 's question
I would say Pretty Hate Machine is probably the best known. My favorite is Broken. You are probably correct about Downward Spiral being the consensus among the fan base as a whole. What I really like about NIN is that I enjoy all of their albums. Many other bands I like have some that I avoid. Probably my least favorite NIN album is Fixed and it’s still pretty listenable.