What do you use, prefer?
I have mostly used KVM with qemu, but I want to try out other things. I have heard of proxmox and all kinds of cool management things, what’s a solid setup that supports easy backups and such things?
KVM and qemu is solid and pretty easy to understand. Basic control of the VMs can be done with virt-manager, which is a basic but solid tool.
https://xcp-ng.org with the up-and-coming Xen Orchestra Lite may be a good option. It’s basically a FOSS fork of Citrix Xen Server. The interesting backup features are locked behind some pretty high paywall, but you can either build them yourself or just use Borg backup on the individual VMs, which uses less bandwidth than XOAs Delta backups anyway.