Xen is still around, including an open-source version. It's not as visible as it used to be but works e.g. XenServer (https://www.xenserver.com/editions). I'd look at this over VMWare anyday.
When I was looking at solutions, most of what I found seemed to indicate Xen is waning in popularity. I considered XCP-ng but since KVM seems to be more preferred now, I ended up going with Proxmox for a few small work (3-5 hosts) and home (1 and 3 host) systems. It’s actually been rock-solid, basically had zero problems with it.
Really feels like Openstack could use a fresh coat of paint and someone to create a nice opinionated distribution of it and challenge some of these f500 customer vmware accounts. It's very powerful, but is as user-hostile as I have personally experienced. Maybe this already exists though with Cloudstack?
