The best replacement for libvirt is qemu.

The best alternatives to libvirt are rated as following:
★★★★★  qemu
★★★★★  lxc
★★★★  ovirt
★★★  proxmox
★★★  vagrant
★  ganeti

Your alternative for libvirt is not listed? Suggest!
Speaking about libvirt, one probably shouldn't forget about xen.

Other search terms related to libvirt and their ratings are:
★★★★★ xen
★★★★ kvm
★★★★ dnsmasq
You have in mind a companion for libvirt and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of libvirt in all years. Click on graph for more.
libvirt
qemu
lxc