Brian Eno - Thursday Afternoon

Laraaji & Brian Eno - Ambient 3: Days of Radiance

Tim Hecker - Haunt Me, Haunt Me, Do It Again

Blood Incantation - Timewave Zero

Christian Fennesz and Jim O'Rourke - It's Hard For Me To Say I'm Sorry

PBK and Jim O'Rourke - Unidentified Again

Oreb Ambarchi - Grapes Of The Estate

Golden Retriever - Light Cones

Kassel Jaeger - Swamps/Things

Growing - Color Wheel

Most of these are probably considered more "experimental" than ambient, but whatever, genres are weird

Edit: formatting

• Tangerine Dream - Phaedra, Zeit, Alpha Centauri

• Loscil - Plume

• Aphex Twin - Selected Ambient Works Vol. 2

• M. J. Harris & Martyn Bates - Murder Ballads

• Mirror - I paint for the love of color, Nightwalkers, A Pilgrim's Solace... Any of them pretty really I love Mirror

• Andrew Chalk - Time of Hayfield, same goes here, Chalk is half of Mirror)

• Thomas Köner - Nuuk

• Michael Bross - Subway Meditations

• Akira Yamaoka - Silent Hill 1, 2 and 3: The Complete Soundtracks to all three

• Jorge Reyes - Mort Aux Vaches, The Flayed God and if that's up your alley be sure to check out Antonio Zepeda as well!

• William Basinski - Melancholia, The Disintegration Loops

• Oöphoi - The Rustling of Leaves, The Spirals of Time and so many others

And some borderline ambient, but might scratch the itch:

• Gavin Bryars - Jesus blood never failed me yet

• Jon Hassell - Vernal Equinox, The Surgeon of the Nightsky Restores Dead Things by the Power of Sound, others from his earlier half

• Rapoon - Vernal Crossing

• Tuu - All Our Ancestors

• The Body Lovers/The Body Haters

• Scott Walker - The Drift, Tilt

• Dead Can Dance - The Serpent's Egg, Into the Labyrinth, Toward the Within, Within the Realm of a Dying Sun

edit: There's too many! I didn't get to Robert Rich, Gas, Jan Jelinek, Muslimgauze, Biosphere and so many others

Anything Boards of Canada is good, but I find their A Few Old Tunes have a particularly good ambient feel.
A Few Old Tunes Vol. 1

A Few Old Tunes Vol. 2

I really like After the Night Falls by Robin Guthrie & Harold Budd.

• Roly Porter - Third Law
• Tim Hecker - Love Streams

• 1 2 3 - Pole
• And Their Refinement of the Decline - Stars of the Lid
• Plume - Loscil
• The Sound of Lights When Dim - Slow Dancing Society

Have been listening to Chihei Hatakeyama's albums a lot while working and studying. Coastal Railroads in Memories is my favorite

Hiemal by Hiemal, they’ve got a bunch of other similar dark ambient albums too

Patrick O’Hearn!

Erland Cooper - Sule Skerry

To be honest, this album is closer to folk, but his more recent stuff is more ambient. I love this record though. The title track is a stunning piece.