I currently use Joplin but I find it's a bit too over-engineered with many features I don't use. For me the best note taking app would:
Be FOSS
Sync over NextCloud / webDAV
Support kind of formatting (markdown for example)
Have ability to create check box lists
Be lightweight and fast to open
Have ability to set remainders and alarms (if possible)
[if possible] as either a windows desktop client or a web client or interface to access notes from work
Now depending on how I like the software, I may change a bit my habits and drop some of those requirements if the soft please me and I find workaround or drop the feature (for example an automated backup can replace NextCloud stuff and I don't use that much the work computer to access notes, so if it's good and I can share the note manually by mail or so, I can live with it).
I think Quillpad would be worth taking a look at. I needed indentable checklists more than syncing so I switched to NotallyX, so I don't remember if it has all of these things, but it seems like a good fit
Sync with Nextcloud (requires the Nextcloud Notes app installed on the Nextcloud server used for syncing)
Backup your notes to a zip file which you can restore at a later time
Toggle between Light and Dark mode
Choose between multiple color schemes
The github (https://github.com/quillpad/quillpad) leads me to believe there may already be a desktop app. Nextcloud syncing looks to currently be experimental
Yeah, I do too. Honestly it's more polished and finished than notallyX I just REALLY need the indentable boxes, that was a feature I used nonstop when I was using keep