Virtuozzo is good for managing virtual instances created with OS virtualization. However it is expensive. SolusVM should work fine for you as interface to manage OpenVZ and Xen. However non of those should be called "control panels".
SolusVM is definitely the best for your money. It has a great interface and you can setup OpenVZ and Xen, which covers all the operating systems. I use it now for my Linux VPS modules and Windows. It's relatively new software, but the developers are working hard to improve it and add new features. I love it.