Obsidian is my go to. But I like NotesNook encryption and interoperability between iOS and desktop. If you want minimal my good friend developed these https://auertools.com/
Discussion
These look pretty good. Could your friend be persuaded to port these to use Nostr as a backend?
nostr:npub1zuuajd7u3sx8xu92yav9jwxpr839cs0kc3q6t56vd5u9q033xmhsk6c2uc how do you feel about reusing the MLS spec for other subprotocols?, like we define a NIP for simple notes, then notes clients create a group with all your devices (assuming it's just for personal usage and only you will see your notes) and use some selected relays to save and sync your notes encrypted using the group key.
Possibly. He built these, I did the design/UX, because nothing else suited our needs - sound familiar...? If he does not have time to do this himself, can he share the code for others to leverage for nostr? Let me ask him...
So he says he does not have time to port them, but the code is open source and he'd be happy to share.