There is something about Notion that makes it feel very well-made and coherent. It’s one of the few apps I use with this inherent feeling of quality (off the top of my head Sublime Text/Merge, Beyond Compare, Things fall into this category of intangible greatness). Every interaction is delightful, and the app scales really well from basic note-taking to decently complex databases with grouping, filters, relations, templates and permissions. It comes with really good real-time collaboration.
On the flip side the software a bit slow to start and uses a lot of resources—it’s based on Electron, but I encourage everyone to try it (the demo on their website is cool!).
This is as close to “painting the back of the fence” as it gets.