I know someone else already mentioned it but I'm going to do the same. Notesnook. I have been using it for around six months now.

I have been looking for the perfect note taking up for a long time. I have some of the same concern as you and Standard Notes looked like a promising app for me but it also looked really overpriced and kind of over complicated.

Notesnook pretty much had everything I wanted. The most important thing for me is that it is completely cross-platform. It has perfect feature parity no matter where you are, no matter if you're on the web app, the iOS app or the Android app, the Mac app, whatever. It has everything on all apps.

It's important to me because some apps are primarily developed for one platform and you can tell that while you pay the same price on another, you're still a second class citizen. And you also get some apps which are in general scattered around feature-wise. So some client gets some features and other don't. It's weird. I mean look at the whole Proton suite between iOS and Android.

It can sync with its own service, it works well enough, and it's end to an encrypted which I love.

And it's fully open source! Which is the cherry on top.

My only gripe with it is its editor. It supports markdown but it's not really markdown. It's a rich text editor with markdown support for formatting which is very different. The results are sensibly the same but more often than not if you copy and paste something that is already formatted from a markdown editor into the app, it won't format it. You will get # and * everywhere but they won't do what they're meant to be doing. Because it's made to interpret Markdown as you type it.

I wish we could get an actual simple, rock solid Markdown editor. But other than that? Notesnook is the nest Note taking app I've used and I've tried plenty.