For me one of the biggest issues with Notion (and to a smaller extent with Obsidian as well) is its ever present UI. When I write (or read) something, I don't want to see 20+ buttons scattered around distracting me from the content.

IA writer got this right, but it's too local and doesn't have colab or better online sync features. Shameless plug – I'm building https://kraa.io/about that's trying to be a writing app with a minimal, yet feature-rich, UI. (better offline and local-files functionality planned)