In terms of Audiobook Players for mobile phones, i tend to divide them into 2 categories:
- Apps which play the media stored locally:
Android Clients: a. Smart Audiobook Player - Versatile, has almost all the required audiobook features. Very stable and one of the oldest players in the market (https://play.google.com/store/apps/details?id=ak.alizandro.smartaudiobookplayer&hl=en&gl=US)
b. Listen Audiobook Player: Newer, has a better UI (in my opinion). Cloud Sync of reading progress (https://play.google.com/store/apps/details?id=com.acmeandroid.listen&hl=en&gl=US)
c. Voice Audiobook Player: Good UI, FOSS (https://github.com/PaulWoitaschek/Voice)
iOS Clients: a. Bound Audiobook Player: Stable with most of the required features (https://apps.apple.com/us/app/bound-audiobook-player/id1041727137)
b. Haven't used any other app
- Apps which work of server-client model
a. Audiobookshelf: New, still being actively developed. Android client though in beta is quite decent. iOS client still needs work. Multi-Platform (https://www.audiobookshelf.org/)
b. Plex with Prologue (https://prologue.audio/) (iOS)/Bookcamp (https://www.bookcamp.app/) (iOS/Android)/Symphonium (https://symfonium.app/) (Android): In terms of ease of use and features, Prologue beats all the other apps however the other apps mentioned provide a good experience