long
So.- Nextcloud: Slow frontend, feels somewhat brittle sometimes, probably the best solution still.
- Seafile: Feels very snappy, I like the "Library"-based organisation. Config can be annoying though and each major version is a chore to upgrade.
- Opencloud: A huge pain to set up properly with Collabora and stuff, if you do not use their exact reference setup. Nice UI, feels half-baked still.
- Synology Drive: Decent, but the desktop app has weird issues. Also not open source.
- Sync-in: Very nice, snappy, simple to set up. Desktop app needs work and faster syncing after file changes, no mobile app at all.
- Hoodik: Fine, but no desktop app :(
- FileRun: Solid, but closed-source
Turns out I have not tried Pydio yet. Well, something to test.