Most all of these are out of print, or so obscure that apparently I'm the only person I know who's ever read them.
- Blame!: Nihei Tsutomu, Blame! anime previously reviewed.
- Blame! Academy And So On: Nihei Tsutomu's art book, weird school side-story to Blame!
- Noise: Nihei Tsutomu, prequel to Blame!
- Digimortal: Nihei Tsutomu. Bleak and awesome.
- AD Police: The serious part of Bubblegum Crisis. The anime is OK but not as good as BGC, the manga are the other way around.
- Black Magic: Shirow Masamune's original epic of an Athena/Typhon bioroid sorceress fighting to free Venusians from an evil AI god Zeus 66 million years ago. The anime takes one minor element, the M-66 combat robots, and turns that into a well-drawn but vapid present-day (1990s) Terminator ripoff.
- Appleseed: Shirow Masamune. "The Promethean X" are the four volumes of a girl and her cyborg boyfriend from a post-WWIII wasteland trying to "adapt" to a city created by and for bioroids, where Human people go crazy. Is civilization even possible for Humans?
- Dominion Tank Police: Shirow Masamune. Bleaker than the very silly anime, but both are kinda light-hearted with absolute doom for humanity.
- Orion: Shirow Masamune. Very weird Buddhist-fantasy-tech. Like steampunk but with mandalas and priests instead of Victorian aristocrats fucking you over. Main character is very much Typhon 2.0.
- Ghost in the Shell 1.5 Human Error Processor: Shirow Masamune, the volume you certainly missed between GitS 1 & 2, which you can find new copies so I won't link to. Here Motoko/Puppetmaster hybrid learns to redesign user interfaces and jump between bodies (mostly taut young female cyborgs, because Shirow's a perv, and who isn't?)
- Lazarus Churchyard: Warren Ellis, an immortal plastic-spiky-boy in a ruined England (post Brexit, ha!) trying to die and failing. Generally possible to get in print?
In all cases, I suggest grabbing the torrent and then just keeping all the cbz, read with your comic reader of choice.