xcp-ng. You can use a built-in mini-management tool (xo-lite) to build the full-featured management tool (Xen Orchestra) from git. There are a couple of maintained scripts that automate the process.
I like it because it is not a bag of parts. Everything is included. It is a VM toolkit that JFW, and it is not what keeps me awake at night
If Proxmox works for you, great. It looks like a very capable system.
The only reason I suggest switching to XCP-ng is if you are fleeing VMware or the warts of your current system exceed your tolerance level. Personally, starting from a greenfield, I would go to XCP-ng without hesitation because XCP-ng is that level of production quality.
I like it because it is not a bag of parts. Everything is included. It is a VM toolkit that JFW, and it is not what keeps me awake at night