My feelings as well. What we really need is a ansible script or a docker file, which would build a Jenkins instance which everyone could use. You would of course need different tools for various build setup and technologies, but CircleCI is far from point and click anyway. I really which I would spend all the time I wasted on their config to build the above. This way everyone could run 5000$/mo of CircleCI on a 50$/mo bare metal.
You might want to try Azure Pipelines. It uses a dual model of Microsoft-hosted build agents running several OSes including macOS, and self-hosted build agents running on infrastructure of your choosing. The team I lead uses for Windows-, Linux-, and macOS-based builds, Microsoft-hosted and self-hosted build agents.
If I finally decide to pull the plug I will probably invest time to build my own setup around OS tooling. Main benefits would be much lower price and independence from lock in. And it's not like one has to build their own solution here. There are tools available.
