While trying to set up a bare-metal hypervisor, before settling on XCP, for the new server, I tried a number of configurations.
VMWare ESXi, which I believe I would still recommend as a first try, has problems with unbalanced memory, so if you aren’t willing to put out the money to properly balance your nodes skip it.
Oracle VM seems like a really great package but there are a couple things to watch out for. The base system is unable to work with NFS loopbacks, that is an NFS share hosted and mounted on the same machine. If you were thinking of doing this, don’t. Use iSCSI instead.
Also, you need to install Oracle VM Manager on some computer. You can run it in a VM but you need an external VM to set this up in the first place and it takes some resources. Alternatively, you can install it on the Oracle VM Server base system. There are some guides for doing this. I found this one to be especially good: http://www.pythian.com/news/30197/installing-oracle-vm-manager-3-0-3-under-dom0-host-or-how-to-save-resources-on-your-sandbox/ But, ultimately I was unable to get the system to work, it frequently crashed often resulting in database corruption (it might be that I was using Oracle XE instead of SE or EE).
My recommendation is to stay away from Oracle VM.
So far XCP has been a great system, albeit not very well documented (XenServer has good documentation that is mostly applicable, but there are a few differences). I will be adding some guides on working with XCP on this site soon.
Update: For ultimate control and easy installability in complicated disk setups, it seems that deploying Xen on Debian is the way to go.