My $0.02:

NixOS is excellent, and actually pretty easy if you’re not trying to do anything fancy (running all services under a single user, etc.). Personally this is my pick because I primarily host services for myself, so down time in exchange for learning a new thing is acceptable.

As I mentioned elsewhere, Debian + Incus is a great minimal and rock solid solution for longer standing services. Although, it’s not composeable :(

More directly to your preferences, I would also recommend considering Rocky. Being in the RHEL ecosystem has its perks (especially with rootless support for podman and podman-compose). I’m also generally a fan of SELinux. Rocky is a little less bleeding edge than Fedora with many of the same conveniences and recent packages. In my mind, for my purposes, that makes it a better choice than Fedora for a server OS.

I tend to not use the webui, so I prefer the similarly useful combination of Debian + Incus (spawned from the LXC project).

Sure, HA isn’t baked into Incus (to my knowledge) but similar to OP I only have one physical box and don’t necessarily care to manage multiple.

That being said, Proxmox is a good solution in the scheme of things and generally a good recommendation.