Even though Debian seems like a good pick, I was just burned by not being able to use one of my install scripts that depends on an Ubuntu PPA. It doesn’t matter what I think of PPA and Ubuntu, that is what people use to distribute stuff officially, including the Git project.
This is especially true for beginners with no Linux experience, those who might pick PopOS! as their main host OS later.
I was a little worried by the fact that Canonical announced they are no longer supporting their “minimal” OS version, which made the container people raise an eyebrow. But I’m sure there will continue to be official Ubuntu images maintained in the standard Docker library. So that’s what beginners should probably use.