Which hypervisors are free with Xen?
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
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.