For context, I'd suggest reading the Wikipedia entry on american primitivism. Anything I could say here would be little more than plagiarism of that article.
1. John Fahey - John Fahey / Blind Joe Death
John Fahey's first record is where the entire genre began. Blending the fingerpicking blues of Charley Patton with the intense classical compositions of Béla Bartók and Charles Ives, Fahey's first record challenged beliefs about classical and folk music, all while starting his own record label and contributing to the burgeoning folk revival in the process. A lot of revolutionary, influential albums aren't all that great to listen to on their own, but John Fahey / Blind Joe Death, is easily one of my favorite records of all time. Fahey would improve his skills on the guitar with time, but the languid, laid-back compositions here are a joy to listen to.
2. Sandy Bull - Fantasis for Guitar and Banjo
Bull was the first musician besides Fahey to experiment with the genre of American primitivism, and he would take the genre to experimental heights other musicians wouldn't even come close to touching until the '70s. As the title suggests, Bull plays guitar and banjo on the record, but what sets the record apart from other primitivism records is his enlistment of jazz drummer Billy Higgins (best known for his work on Ornette Coleman's game-changing The Shape of Jazz to Come). The addition of a drummer allows Bull to flesh out the sound of the genre, and masterpiece of the record is "Blend", a 22-minute odyssey that showcases the best both musicians have to offer.
3. George Stavis - Labyrinths
Labyrinths continues where Fantasias for Guitar and Banjo left off, offering a psychedelic, banjo-led take on the genre pioneered by the guitar-slinging Fahey. It's not quite as compositionally immaculate as Bull's album, but Stavis' work on the banjo is incredible. The instrument is naturally very resonant and percussive, which are two factors that Stavis uses to his advantage in putting together this very spacious and psychedelic record.
4. Leo Kottke - 6 & 12 String Guitar
American primitivism was founded on the roots of one idea—combining the finger-picking guitar style of country blues with the composisional complexity of classical music. Many artists have taken the genre into psychedelic, experimental directions, and Kottke is absolutely not one of them. 6 & 12 String Guitar was the biggest commerical success for John Fahey's Takoma label, and it's easy to see why. It's an incredibly pleasant, soothing folk album. While entirely different than Fahey in style, Kottke's guitar playing is just as hypnotic, offering a heavy, percussive style that's a delight to listen to.
5. John Fahey - Fare Forward Voyagers (Soldier's Choice)
Fare Forward Voyagers is the absolute pinnacle of American primitivism. That might be a bold statement to make in any genre, but it's hard to think of an album that so clearly stands above the rest of its genre other than Fare Forward Voyagers. The simple blues style that Fahey began with on Blind Joe Death is still present, of course, but the compositional style is so much more rich, vivid, and experimental. Fahey amps up the influence from experimental composers like Ives and Bartók while bringing in major influence from the ragas of hindustani classical music, and the result is easily one of the best records of all time.
6. Robbie Basho - Visions of the Country
After Fare Forward Voyagers, it almost seemed impossible for the genre to move forward. Fahey's opus was easily the best album in the genre, so it seemed impossible to improve upon it further. Robbie Basho's early records on Takoma were pretty straightforward primitivism released, very much indebted to the work of Fahey. They're solid records, but his masterworks came once he moved to Vanguard records. Venus in Cancer and Zarthus are both brilliant, but Visions of the Country is his masterpiece. Vocals in primitivism are almost unheard of, but Basho's trembling, operatic vocals fit perfectly with the pastoral landscapes evoked by his brilliant guitar work.
7. Jim O'Rourke - Bad Timing
Let it be known: this is my absolute favorite album of all time. Not only was in the album that got me into American primitivism (my favorite genre of music), it also led me down a rabbit hole of similarly out-there, experimental records, and for that I am eternally grateful for this beautiful record. It's also an absolutely brilliant primitivism album, and easily the best of the genre's modern revival. This was O'Rourke's first conventional album following years as an experimental noise provocateur, and it sounds unbelievably natural. His guitar work is laid-back and agreeable, and the pop influence that guides the composions is brilliant, and something never before seen in primitivism. If you check this out, make sure to follow it up with a listen to the equally fantastic Eureka.
8. Six Organs of Admittance - Dark Noontide
Six Organs of Admittance, the nom de plume of guitarist Ben Chasny, has undergone many different genre shifts over its 21-year run as a project. Ascent is a psychedelic blues rock project, Hexadic takes influence from noise rock, The Manifestation dabbles in spoken word, and Luminous Night is Chasny's droniest album. With all these styles, it can be hard to pick a favorite, but Chasny's best work always lies in his experiments with American primitivism, and Dark Noontide is his best album in the style. Chasny's various other styles are all accounted for here, making for one of the most experimental, psychedelic records in the entire primitivism genre.
9. Glenn Jones - This Is the Wind That Blows It Out: Solos for 6 & 12 String Guitar
John Fahey had something of a comeback in the mid-to-late '90s. After falling into relative obscurity following the release and subsequent commercial failure of Fare Forward Voyagers, Fahey's profile was raised after an article in Spin magazine revealed a whole new audience of experimental alt rockers. Fahey collaborated with Sonic Youth, and worked heavily with Jim O'Rourke, who produced his 1997 album Womblife. Fahey also collaborated with Cul de Sac on their 1997 record The Epiphany of Glenn Jones, and band member Glenn Jones himself took the experience to heart, releasing his own primitivism album seven years later. This Is the Wind That Blows It Out isn't the most original primitivism album, but it's one of the album's that does the genre's original style the best. It's 43 minutes of hypnotic, brilliantly composed guitar, and I love it to death. Also, the chick on the album cover is absolutely FEELING it.
10. Jack Rose - Kensington Blues
The modern class of American primitivism is centered around experimentation, psychedelia, and playing around with the typical conventions of the genre, and of folk music as a whole. Very few modern primitivism guitarist wear an influence from blues on their sleeves, except for Jack Rose. Rose's love for blues and classic country shines through every single track on Kensington Blues, one of the most serene and straight-up beautiful primitivism albums of all time.
