XenServer has several value add features over other options:
1. XenServer installs on bare metal.
2. XenServer requires no additional OS.
3. XenServer is easy to install. Their motto is "10 minutes to Xen"
4. XenServer includes templates and wizards to easily create both Windows and Linux machines.
5. XenServer has a multi-server GUI tool to perform management tasks. OSXen is CLI only on a per server basis.
6. XenServer has integrated storage support.
7. XenServer can allow VM's to be seen and launched from a Resource pool of multiple servers.
8. XenServer includes high performance drivers that reduce the Windows vm overhead from 30-40% to 2-7% on XenServer.