Too Long; Didn't Read
If I had to choose my favorite today (October 2021), Notion was my overall winner, where if I was starting completely from scratch, Notion filled the majority of my needs and had a good user experience that I was excited to work in. It was easy to organize, edit, collaborate, and more in a way that facilitated as many automated processes as possible.
However, I am not starting from scratch, and there are tradeoffs to migrating interfaces. So for that reason, we have decided to stick with Confluence, as all of our content is already there, we already pay for it, and it doesn't require our team members to sign up for a new account anywhere. A bit anti-climactic, but none of the solutions we found offered enough more than Confluence to be worth the resource investment to migrate.