First of all I'm a Fedora user and podman/buildah have been recommended since Fedora switched to cgroupsv2.
But also I prefer using open source projects from communities and companies who are based around open source. Google do contribute a lot to open source but they're primarily an ad company who want your data. So consider using buildah a type of boycott. ;)
I use buildah privately whenever I need to quickly make an image to test something, it's so simple to use in bash. It's also very simple to add to existing images while you're testing it. So it was just natural to continue using it in CI pipelines.
I only ever used one command for kaniko so I'll admit I know nothing of it, and that was 2 years ago. But buildah feels a lot more accessible because I learned all the different shell commands that correspond to the Containerfile format.
I found that it was convenient to reuse Dockerfile rather than learning a new domain specific language and also for some reasons I was not able to use podman inside docker when I tried (our CI runs in docker containers) while kaniko works well inside docker. I'll have a second look to podman, maybe it's better now.
