Linux

None, I use Docker for Linux, and Proton (Heroic) for Windows.

But if I had to pick a virtual machine: libvirt with virt-manager as a frontend, which uses KVM for virtualization.

GNOME Boxes because it doesn't require 5 academic degrees to set up and I'm a GNOME user.

Qemu/KVM and Virt Manager. I have three VMs that I pass my GPU to: a Hackintosh, a Windows 10, and and Windows 7.

virtmanager as frontend for qemu/kvm. I tried the commandline but it's too annoying

Usually VirtualBox. It's easy and free.

KVM

(VMware is proprietary software)

KVM + Qemu + libvirt + virt-manager = ❤️

I used KVM with virt-manager for a long time. Even ran a gaming VM with GPU pass-through.

Then I created a Docker image with Linux, Gnome, and novnc so I can spin one up instantly with little resource overhead and control it from any web browser.

Virtmanger-kvm-qemu

I use qemu, but with Quickemu 'cause I'm lazy lol.

I use virt-manager, aka Virtual Machine Manager. Using this specifically because of the winapps for Linux repo has instructions on how to get Windows apps to run through the VM to be integrated in a Linux environment.

I'm kinda lazy so when I need one, I just use Gnome Boxes and it's pretty easy to setup.

Qemu+Kvm with virt-manager is my boy nowadays. But I'm not a heavy user of Vms, just experimented with this to build some Flatpak. But plan on trying out other distributions, just for science. It wasn't easy to figure out how to share a folder, and I could not get drag and drop or clipboard share to work. Still though, its faster than any other solution. I used VirtualBox in the past, which was easy to work with.

Proxmox seem powerfull

It's a Type1, not Type2
https://en.wikipedia.org/wiki/Hypervisor#Classification

Gnome boxes.

Based on QEMU+KVM so it's quite robust. It works pretty well, plus it has various little features working out of the box that in some other software is a pain in the arse to configure.

Sticks out a bit on my system due to still being GTK3, but there is a GTK4 prototype out that usually works well.

E: downvoting anybody who says Gnome Boxes because you use a different virtual machine frontend is laughably pathetic lmao. Some people in the Linux community are such losers lol

I use libvirt to do all my kvm/qemu stuff on my server. Using cockpit-machines web UI as a frontend. On my workstation if I ever need a VM I usually turn to Gnome Boxes for simplicity

@Mwa qemu :blobfoxcomfycomputer:

Virtmanager and qemu/kvm

Virt manager for qemu. I use docker and distrobox for Linux distros

I recently managed to use my windows partition (for dual boot) as a disk for a qemu. I don't use it but really cool trick anyways. Tutorial here

Also it's not very healthy for windows since it is not designed for constant hardware changes. But idc all my apps are installed on D: so I can just reinstall it without thinking about it much

So far I’ve been fine with some Oracle Virtualbox and some using the VM Manager that was in my distro or maybe I downloaded it. It’s just called Virtual Machine Manager made by Red Hat. Libvirt.

Between those I’ve been able to do everything I have needed.

Linux: qemu

OpenBSD: vmm, qemu when vmm isn't good enough

Virt-Manager, even works remotely via SSH.

Virtualbox

If I'm running another Linux distro that will be happy under the host kernel then I use LXD (or Incus) containers. Otherwise it's QEMU+KVM or occasionally Virtual Box.