Thanks!
docusaurus.io is the next tool on my list to try out, it looks promising. I think it's better suited for smaller projects, with a lot of things out of the box. I haven't seen an API company using it yet though.
Station is something I've used in the past, because I was working for Nexmo at the time. The team at Nexmo / Vonage won a few awards because of it for the best Developer Portal a few years back. It's open source now, and the cost to setup might be higher than the other two, but a lot of the design decisions make sense for an API portal. It's also super fast once deployed, and that helps a lot with developer perception. https://github.com/Nexmo/station
disclaimer: I'm the founder, happy to show you around :)