I submitted this thread as well: https://news.ycombinator.com/item?id=19579216

I've been into program to music to: https://en.wikipedia.org/wiki/Aleatoric_music

If you want indiscernible lyrics: https://www.youtube.com/watch?v=uz47h75_FJo

(Not sure this fits the criteria of 'decent')

I like long pieces that distort my sense of time and concentration and give texture to the feeling of being in the zone. https://www.youtube.com/watch?v=1ZZ0DYIkaP8