I've updated this list to include some descriptions because everybody else has and I should have in the first place.
In alphabetical order:
Bruce Cockburn - Dart to the Heart. Some of Cockburn's most beautiful songwriting and acoustic guitar playing highlights this collection of love songs. This album consistently makes me cry and smile, often simultaneously. It also has the gorgeous "Closer to the Light," a tribute to Mark Heard written after his passing.
Dream Theater - Octavarium. I could have also listed Six Degrees of Inner Turbulence, but this album is a bit better concentrated. Chunk, groove, brains, and soaring majesty in equal doses. One of the greatest prog-rock albums of all time. Worth it just for the orchestra coming back in for the climax.
Peter Gabriel - Security. Seriously, Gabriel's Sgt. Pepper. This is the album that made me start taking music seriously. A sonic masterpiece indeed, one of the first all-digital recordings. "San Jacinto" demolishes me.
Genesis - Selling England by the Pound. The purest example of early Genesis, from Gabriel's a capella intro through the mournful, unsettling reprise at the end. Foxtrot is also great, but there's storytelling in the instrumental passages of "Dancing with the Moonlit Knight," "Firth of Fifth," and "Cinema Show" that I've never heard before or since.
Mark Heard - Dry Bones Dance. This is an album that I love more every time I hear it. Zydeco, dixieland, folk, country, and rock influence create a sonic songwriting gumbo matched only in its brilliance by Heard's lyrics. "Mercy of the Flame" is probably my favorite song in the world right now.
Joe Jackson - Heaven and Hell. How to choose one Jackson album? You pick the one that's most unique and least likely to ever be duplicated. This one is a neoclassical techno-orchestral song cycle based on the Seven Deadly Sins, featuring Suzanne Vega (lust), Brad Roberts (sloth), Jane Siberry (envy), Nadja Salerno-Sonnenberg (the devil as violin), and the usual cast of Jackson's genius collaborators. It was even performed as a musical by the Boston Conservatory last year. I'd like to point out that they stole my Night and Day idea, highlighting the importance of some theatre in Richmond helping me produce it professionally as soon as possible.
Rich Mullins - A Liturgy, a Legacy, and a Ragamuffin Band. Again, how to choose one Mullins album? Mainly for the opening-side trilogy of "52:10," "The Color Green," and "Creed," all three of which astonish me every time. Mullins may be the most passionate songwriter I have ever heard, and this is his most passionate and best-produced work.
Sam Phillips - A Boot and a Shoe. So sad, so smart, so obtuse, and so sexy. Sam has a new album coming out this summer, and it's worth counting the days until.
The Who - Quadrophenia. A double-album of teenage angst written with such passion and poetry that it should be issued at the door of every high school. "Love, Reign O'er Me" is simply an irreplaceable song; there is nothing like it.
Yes - Tales from Topographic Oceans. Massive, pretentious, bloated, obscure. Gorgeous. Don't change a note.
My apologies to brilliant albums by Kansas, T-Bone Burnett, Jane Siberry, Pete Townshend, King Crimson, the Beatles, Dan Fogelberg, Cindy Morgan, Charlie Peacock, Tom Waits, Steve Hackett, and so many others who didn't make the list. It was quite exclusive and hard to get into.
What's next, ten favorite plays?