I could think of some more bands to add to that list.

I love Zoviet France and Maeror Tri so hard-bam much.

Sleep Research Facility
Biosphere
Eluvium
Jónsi and Alex
Altus

Nadja
Aidan Baker
Lotus Eaters (with Plotkin, O'Malley, Turner)
Growing
Locrian
Belong
Everlovely Lightningheart

n u a g e s is amazing!

Harold Budd is also really good. He's collaborated with people like Brian Eno and Cocteau Twins.

If I could add some of my favourites

Tim Hecker
Coil
Ulver (late)
Bill Laswell
Terre Thaemlitz
The Caretaker
Fennesz
GAS
Richard Pinhas
Z'EV
Muslimgauze

J.M. Jarre, Tangerine Dream, Klaus Schulze, Isao Tomita, Ryuichi Sakamoto, Ashra, etc.