For your specific use case of photos, Immich is the front runner and a much better experience. Sadly for the general Dropbox replacement I haven't found anything either.
For a general file sharing / storage solution there is also OpenCloud: https://opencloud.eu/de
It's what I want to try next. Written in go, it looks promising.
Look into syncthing for a dropbox replacement, have been using it for years, very satisfied.
I'd say Ente-photo is at least as good if not better than Immich.
There is also "memories for nextcloud" which basically matches immich in feature set (was ahead until last month), nextcloud+memories make a very strong replacement for gdrive or dropbox
I replaced all my Dropbox uses with SyncThing (and love it). I run an instance on my server at all times and on every client.
Does its iOS/Android app automatically backup the photos in the background? When I looked into Immich (didn't try it) it sounded like it was more of a server thing. I need the automation so that my family can forget about it.
I use Syncthing as a Dropbox replacement, and I like it. I have a machine at home running it that is accessible over the net. Not the prettiest, but it works!
I love immich, too, but I have also ran into a lot of issues with syncing large libraries. The iPhone app will just hang sometimes.
I too have found Syncthing + Filebrowser to be a sufficient substitute for Dropbox.
Have you looked into https://filebrowser.org/? While it's not drop-in replacement for Google Drive/Dropbox, it has been serving me well for similar quick usecase.
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> Sadly for the general Dropbox replacement I haven't found anything either.
I had really good luck with Seafile[0]. It's not a full groupware solution, just primarily a really good file syncing/Dropbox solution.
Upsides are everything worked reliably for me, it was much faster, does chunk-level deduplication and some other things, has native apps for everything, is supported by rclone, has a fuse mount option, supports mounting as a "virtual drive" on Windows, supports publicly sharing files, shared "drives", end-to-end encryption, and practically everything else I'd want out of "file syncing solution".
The only thing I didn't like about it is that it stores all of your data as, essentially, opaque chunks on disk that are pieced together using the data in the database. This is how it achieves the performance, deduplication, and other things I _liked_. However it made me a little nervous that I would have a tough time extracting my data if anything went horribly wrong. I took backups. Nothing ever went horribly wrong over 4 or 5 years of running it. I only stopped because I shelved a lot of my self-hosting for a bit.
[0]: https://www.seafile.com/en/home/