What are some alternatives?
When comparing Proxmox Virtual Environment and virt-manager, you can also consider the following products
oVirt - oVirt is a virtualization management application.
VirtualBox - VirtualBox is a powerful x86 and AMD64/Intel64 virtualization product for enterprise as well as...
Virtualizor - Virtualizor is a powerful web based VPS Control Panel.
QEMU - QEMU (short for "Quick EMUlator") is a free and open-source hosted hypervisor that...
VMmanager - VMmanager is a virtualization management software, which presents a perfect tool for creating virtual machines, providing VPS services and building cloud infrastructure.
OpenStack - OpenStack software controls large pools of compute, storage, and networking resources throughout a datacenter, managed through a dashboard or via the OpenStack API.