I use Retro Music. What advantages would Symphony have?

I’m not sure if they’re popular or not but I didn’t see them mentioned in this thread and I rely on these fantastic open source apps daily:

1. AntennaPod – podcast app
2. Orgzly – Todo lists / reminders / notes via org files. Can be synced via syncthing.
3. Aves – gallery app
4. KeePassDX – keepass client
5. Prognoza – weather app
6. Olauncher – minimalist launcher

Honourable mention: Harmonic – hacker News app. Not “essential” by any means but it’s quite good.

Edit: added prognoza and olauncher

Magic earth is not open source, if that matters to you.

Voice is wonderful https://github.com/PaulWoitaschek/Voice