My company is using Confluence, I was a bit skeptical at first, but it is quite easy to use, and there are interesting plugins like Gliphy to draw models, or sw architectures. And this is also usable by non technical people. But this is likely a costly solution for a small team.
For my personal note taking, I am using a free tier gitbook[0]. What I like is that, under the hood, it is "only" git managing markdown files and you can sync with a github account.
So even if gitbook stop working tomorrow, you still have your knowledge base in MD files, which is nice.
[0] https://www.gitbook.com/