Since I created this thread, I'll start.
1. Nirvana- In Utero (1993)
It's true that Nevermind is the Nirvana album that everyone talks about, and rightfully so. And yes, Nevermind is perhaps the more important album as well. But, In Utero, Nirvana's third and final studio album, is perhaps their finest work.
Musically, it combines the rawness and noisiness of Bleach with the Pop stylings of Nevermind. You have songs that are noisy and generally about as non commercial as any platinum selling album has the right to be (Scentless Apprentice, Milk It, Tourettes), as well as more radio friendly, glossy, and more accessible songs (Dumb, Heart Shaped Box, Apologies). You even have songs that offer a mix of both styles (Serve The Servants). And amazingly, all of those styles mesh well together. The noisy songs pummel you with their rawness and aggression, while the poppier efforts provide sweet relief from the onslaught of noise. The songs that fuse both styles give you that perfect mix of tension and calm.
The songwriting was also improved. The songs this time were more personal, and contained lyrics about anything from inner pain to boredom. Rape Me was a very blunt anti rape song that received quite a bit of controversy in its day. Serve The Servants, on the other hand, with it's opening lyric "Teenage angst has paid off well, now I'm bored and old" forces you to feel Kurt's disillusionment with the music industry. Nirvana has never sounded as potent as they do on this album.
Simply put, Nevermind IS the album that gets all the attention. And Nevermind IS a great album. But In Utero is superior in every way. Though it doesn't receive the same hype and glory, In Utero is Nirvana's true masterpiece.