That’s good as well, of course. I use QEMU with virt-manager and cockpit on my office workstation running EndeavourOS and it’s glorious. Keeps Windows from ever being installed on the bare metal.

From a usability perspective, though, I think Proxmox lowers the barrier to entry, as the web UI feels considerably more powerful out of the box than cockpit. An interesting bonus is that you can add it to an existing Debian install, including one with a DE, though it’s not something one would want to do in production.

Libvirt is great, been using it at home to run VMs for ~10 years now.

Depends on what level of responsiveness you need from the support team. I run it in my home lab and haven’t needed to raise any tickets as all the info I need to solve problems is readily available on their forums or in assorted blog posts. A company relying on it for their critical infrastructure would probably be best-served with Standard (4-hr response within a business day) or Premium (2-hr response within a business day).

If those still aren’t quick enough it may be worth looking into a partner of theirs, or into another commercial option altogether. I’ve interacted with the Red Hat support team on some high-severity issues and they are top-tier; that was unrelated to virtualization, though, and they tend to push the Red Hat Enterprise Virtualization solution quite hard. I’m talking a response time of minutes.

If I’m using kvm on any standalone (non-clustered) hosts on the data center it’s typically on Ubuntu LTS, knowing that the company I work for has a Canonical support agreement in their back pocket, but we haven’t needed it.