I have tested Obsidian and Notesnook so far.
There are several things I would like:
End to end encryption
Synchronisation between different Smartphones (Android) and Computer (Linux und MacOS). An application is preferred over using the browser.
Format the notes (rich text editing). Markdown preferred.
The ability to export the notes (md and PDF would be great)
The ability to add pictures to the notes (Notesnook doesn't allow this on their free plan).
The app should be available outside of the Google ecosystem. Same goes for the subscription.
A cheap monthly subscription (I'm using the notes in a non commercial way) or one time fee and selfhost.
Things that put Obsidian first in my list (beside some cons I'll list):
Pro:
I really do like many things Obsidian does and offers. The overall UI is great. It's more "visual" (Graph, note structure) than Notesnook in my opinion.
Big collection of (community) plugins (currently it's just "nice to have", nothing important right now).
Cons:
The mobile app is only available through the Google Play store, which is something I would like to avoid as mentioned earlier.
The ability to sync is a paid service with a monthly price of 5 USD (per month, per user).
Its closed source.
To wrap it up: Both (Obsidian and Notesnook) have all the functionality I need for my personal usage but I dislike the price.
Are there other apps including E2EE sync functionality I should look into?
Note: I tested Standard notes but found it to be not intuitive. Should I try it again and invest more time?