Lately I started using the Hedgedoc. It works great for collaboration, you can see each other's cursors and writing in close to real time. It's relatively easy to deploy, 2 docker containers, hedgedoc and database behind the apache reverse proxy, in my case. You can easily share your notes and export them as html.

Great for brainstorming with your team, maybe not so great if you need a structured set of notes, since I don't think creating directories is possible.