I like Incus too, well maintained, feature rich, and still easy to use. It's missing its own UI though. Right now the Incus maintainers are just patching LXD's UI, but that's diverged enough that they can't really depend on it going forward. There are other good open source options out there, but I built ixui because I like Proxmox's UI and wanted something closer to my own taste in UX.