As much as I’m a fanboy of Nextcloud, it wouldn’t be my notetaking tool of choice. Yes, it has a notes app, but that’s a thin veneer of bare-bones text editor over a loose collection of files. There’s no interlinking, no content besides text. I tried, and I couldn’t make it work. If you want to go this route, especially hosted on a non-public place, I’d stick with the loose text files, as it’s far less overhead.
Since it’s Evernote you’re getting away from, and not necessarily a wiki you’re running *to*, how about something like Joplin? That’s far closer to Evernote, you can link to other notes.
Of course, it all depends on the workflow, as you already mentioned, so maybe I shouldn’t wave $RANDOM_TOOL in your face to distract you from getting a clear view of that, first. 😉