We will have paid versions of GitHub (Teams) and Google Workspace for email / calendar and docs.
I did look at notion, clickup but I honestly think I prefer limiting our spend on an extra tool. What I like about notion is how its got a wiki structure, and this is where G-Docs leaves us short. The performance of notion also left me unsure, a few too many times looking at a white page for 5-10 seconds waiting for it to load. We will use G-docs for all our documentation, but I often find there is a cognitive load trying to store and file everything, not to mention link it within some sort of ToC. I find G-docs can quite easily end up 'feeling' messy' unless you keep constantly on top of it.
Another thing of course is GitHub, I feel confident using this for kanban boards, project management etc.
There is https://youneedawiki.com, but I again I am hesitant to subscribe to another tool yet again, as we are trying to keep things costs lean.
We went with notion and while it was kind of fine in the beginning the performance has degraded more and more. Sometimes things do not load at all or it takes forever.
What does notion do? Instead of fixing performance they work on Notion AI to make writing easier. Not sure how other people are using notion but I am never writing in full sentences or paragraphes anyway. It's a way to store notes and bullet points 90% of the time.
Anyway, most important for me is to have a way to create a kanban board. Discussions can happen async inside of the tickets which is a kind of documentation in its own.
What I have learned is to start with as little structure as possible. Most people don't ever look into notion or a wiki ever again and everything that's being put in there is basically dead in this moment. Even worse than no documentation is often wrong and outdated documentation.