I thought building on TipTap would take too much time but I was wrong. I've looked into TipTap extensions and it seems that in less than a week you can build a very decent Notion-like editor. So we will be rebuilding everything with TipTap soon.
Initially I chose Blocknote over EditorJS because I wanted draggable blocks / something that feels more like Notion. But it wasn't a good call to make the decision based on that.
It isn't easily extensible (we wanted to be able to add images with drag-n-drop). From the moment you need to extend, it felt like it was faster to rebuild things directly with TipTap