What are some alternatives?
When comparing OpenNebula and Virtualizor, you can also consider the following products
OpenStack - OpenStack software controls large pools of compute, storage, and networking resources throughout a datacenter, managed through a dashboard or via the OpenStack API.
Proxmox Virtual Environment - Proxmox VE is an open-source server virtualization platform to manage KVM virtual machines, LXC, software-defined storage and networking, HA clustering, and multiple other out-of-the-box tools on a single solution.
oVirt - oVirt is a virtualization management application.
VMmanager - VMmanager is a virtualization management software, which presents a perfect tool for creating virtual machines, providing VPS services and building cloud infrastructure.
Scalr - Scalr is cloud management software for public & private infrastructure
Morpheus - Morpheus is integration software designed to help major cloud infrastructure work in harmony. For example, if a company has assets on both Google's and Amazon's cloud services, Morpheus helps bridge the gap to improve productivity.