Concerning audiobookshelf, I see it other way around, because I think audiobookshelf came after - so it's contender to audioserve. But it is definitely nice app. I tried and did like some things (especially turning books into HLS streams), however I ran into couple of issues, when trying:

- audiobookshelf requires some rules for directory structure (which caused that some subfolders from my collections were not loaded), audioserve serves any directory structure

- bigger collections - for collections with 10k audiobooks audiobookshelf was just too slow it went on for couple of hours loading before I kill it. Audioserve is able to handle within collections scan in tens of minutes.