I can speak at least on behalf of containers that are based on Fedora RPMs and should serve similar purpose as those we ship as default images for development purposes in OpenShift (python, ruby, nodejs, postgresql, mariadb, etc) and that we often call "SCLorg container images".

We've used Fedora infrastructure for a long time, but kept experiencing various issues (see more at [1]) where we could not build container images for days or weeks. There was also not enough automation, and the naming conventions did not work for us perfectly either. So, we decided some time ago to move to quay.io/fedora [2] and never regretted.

There is some automation we have set up to push images to quay.io automatically after each commit [3], so feel free to take an inspiration.

Overall, I think quay.io is the best place for distributing container images, it's just about picking right namespace that's the most valid for the particular container image, and github.com works fine for us to keep sources on, although that's everybody's own choice; containers/ namespace in dist-git might work well for the purpose of keeping sources somewhere.

[1] https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/EOJB6WUY2PKS5VOTVN6FG5PLN2SAKSNY/
[2] https://quay.io/organization/fedora
[3] https://github.com/sclorg/s2i-python-container/blob/master/.github/workflows/build-and-push.yml