Depending on the nature of your needs wrt version control, and how you want your editor to provide annotations, that will shape what solutions work for you. Those are pretty important considerations you will probably want to clarify, to get good advice. Also your comfort with self-hosting.

I’ve personally switched to silverbullet. It offers some really cool features, but I don’t think it’s going to provide the things you want in a way I suspect you’d like.
For example, annotations would be directly inline, not in a little sidebar. And there is no versioning to tell you who made what edit, when; you have to self host it, and provide your own backups at whatever schedule you want, separately from the app. And the really cool features probably aren’t going to be useful for the manuscript itself, it’s things like smart linking to sections of pages, and the ability to embed search queries of your docs directly in a page.