I intend to make this a more robust list in the future, but for now, this will just contain youtube links.
Aphex Twin - Stone in Focus
This song is super relaxing. I often keep it on in the background while I work. It helps block out the construction and siren noise from outside. I like the rest of Select Ambient Works 2, especially track 3, but this is the track I'd bring up if you asked me about it.