Debian.

This is the future so Virtual Machines and containers are where most of the stuff will end up anyway. If you need a specific distro it’s minutes away with a VM or container.

If you think there’s a chance you might want some Redhat cert for a job at some point it might be the time to jump to Rocky, and I’ve never used Proxmox so I can’t comment except to say that if I come into two fairly large computers for self hosting, the first one will get Rocky so I can get much more familiar with it, and the second will get Proxmox.

It’s all systemd anyway.