It's important to me to make this statement, for two reasons: 1) one man's liberty may be another man's stumbling block, and so this warning is posted; art is not exempt from scrutiny, divine or human, as many artists would have you believe.
I do not rank these among each other. They are all incomparable pieces of musical art.
Genesis (1973)
I often consider this my favorite secular album. You can feel that Yes-like majesty, but from a working-class musical point of view. The music transports you to a Renaissance-like dream world without leaving modern-day (well, early 70s) England. The melodies, hooks, guitar riffs, and drumming work their way deep into your bodily systems, but would you expect less from Peter Gabriel and Phil Collins (who even sings one song) and company?
Paul's Boutique
Beastie Boys (1989)
The Beasties at their finest, and therefore rap at its finest. Lyrically vulgar at times but always clever from a secular perspective. They weave classic rock riffs and pop culture references into each song, making the album catchy and fun from start to finish.
Achtung Baby
U2 (1991)
I'm not a rabid U2 fan--like zillions of people rightfully are--but it is obvious that they have written many many great songs. Achtung Baby is full of them, unrelenting. Sonically superb start to finish. If someone dared me to present evidence to refute his contention that Achtung Baby is the greatest rock album ever produced, I'd likely keep my mouth shut.
Mezzanine
Massive Attack (1998)
Their beats and rhythms and textures and hooks on each and every song are so juicy and enjoyable. Crank up the volume and be mesmerized. You may never put this CD down; you'll know what I mean when you hear it.
Toxicity
System of a Down (2001)
Lyrically, they're like Ionesco (think La Cantatrice Chauve) put to music. Musically, they'll never be imitated. Their rapid and abrupt changes in pace and mood are unique among bands and done so very smoothly, comfortably, and naturally. The musicians and producers are top-notch, and they rock as hard as anybody without losing a pop sensibility. Best hard-rock album ever hands down.