We* defaulted to using slack/gdocs as the de-facto knowledge management tool, quickly realized that's not the way to grow and started looking into a dedicated solution. I used confluence and a few wiki solutions before, both in context of a tech team in a large investment banking institution, startups and community organizations. In the end it was a close call between Confluence and a Slab, we decided to go with Slab. It is simple and straightforward to use for both devs and non-devs in the team. The Slab devs have been very responsive and added an app integration we really needed (for diagramming) in a matter of days, which was impressive.
* My team makes a hardware product that has a lot of complexity (6 levels, from product design to game engine)