Depends. Are you happy with MacOS and want to stay in the Apple ecosystem?
If yes, then just keep it. It is perfectly tailored for your hardware.
If you are annoyed by it or want to try out something new, then try Linux.
The 2015 MBA has a Intel CPU afaik and general hardware support should be fine from what I've heard.
Instead of Ubuntu, I would recommend Fedora, either the Gnome or KDE variant. If you prefer minimalism and the coherence/ well-thought-outness of MacOS, then use the Gnome ("Workstation") variant, and if you prefer customisability, then the KDE-spin.
You could also take a look at the Atomic variants, they are a newer concept with a few benefits (and also drawbacks) compared to the regular versions.
As a small tip: no matter if you decide for the mutable or the atomic versions, use Distrobox! While Python is pre-installed, it is a system dependency, and you wanna keep your dev environment isolated from your host OS. If you wanna change the Python version for example, this might otherwise brick your install.