Libvirt/qemu with either virt-manager or cockpit to control them. Alternatively there are various wrapper projects for qemu that hide the complex command line from you.

If you are using Linux, it does not get any simpler than Gnome Boxes. If you need more options, virt-manager is still fairly easy to use.

I’m not sure which os you use but i’ve been using qemu. It’s a little bit more advanced than vmware or virtualbox but is very powerful when it comes to virtual machines. Depending on the specs on your host you can also emulate other processor architectures with it as well.

Proxmox will do 90% of everything you need, coming from VMWare/EsXi. It can import and read your existing vmdks.

Feels like we need a sticky for this, as it’s an on-going discussion, with a lot of details/quirks.

I’m currently testing TrueNAS Core, as they have a vast commercial side including NAS hardware - I think they’ll be around for a while, and they have the resources for continued development.

With friends in the SMB IT space, we’re trying to figure out a migration path for their clients.

Some other options (off the top of my head)

KVM which is Linux native

Proxmox

Incus

Proxmox is VMWare light in a good way.