I’ve been making my “the one” for years (off and on) now. I’m getting closer with https://github.com/MangoCats/Lempi - but it’s still got a big cost up front that I’m under-motivated to address because I’ve already paid (segmenting songs, IDing them in MusicBrainz, analyzing them, trimming lead-in lead-out points, etc.)

The thing I like the best about Lempi is that it does “shuffle play” with a reasonable intelligence, auto-selecting a good subset from my collection based on example songs that I want to hear “things like this” during certain timeslots of the day. I can just let it run anytime / all the time like a radio station and not think about choosing my playlist.