We use GCP Cloud Build for most of our CI needs, and then Argo and Kargo to deploy things.

Cloud Build is generally pretty straight forward to use and we rarely have to mess with pipelines after initial setup. It's easy to make new images with any tools you need for your build process.

Triggers and repo connections are a little annoying to setup, but if you get a little terraform module set up it's not too bad.

Still love CircleCI. They're one of the most mature in the space. Not as flashy as GHA but gets the job done.

Why do you need a CI at all? You can use a queue like Oban on your own server to kick off jobs. And with AI you can add new jobs, so long as they are well defined, in a few minutes and schedule them however you like. I only recommend this because I use a similar system. If you are planning on GitHub's recent instability to be improved in the future, I would not get your hopes up, they have a long history of instability.