The single most important usability feature missed by our less technical
users who migrate from VirtualBox is a one click import/export of VMs
and their config settings.
I was optimistic about the Gnome Boxes effort on Govf lib but
unfortunately it was never realized and I would hesitate to recommend it
because libvirt/virt-manager has the security advantages of sVirt.
An ideal solution would work across all KVM frontends.