I listen a lot to ambient as well, but I liken it to drinking tea, which I normally do, and save coffee (the bpm stuff) for crunchtime.
My ambient go-to:s are (in no particular order):
Roedelius
Harold Budd
Tim Story
Brian Eno
Roger Eno
Hannu
Offthesky
Deaf Center
Message To Bears
Pjusk
Everything Is
diatonis
Build Buildings
The Echelon Effect