Depends on what you intend to use it for and what your target market is. For the consumer segment SolusVM just works although if I were starting now I probably would not go with them due to their slow progress and development. Virtualizor seemed promising to me during trials.
We prefer Virtualizor XEN for our Virtual Servers. Although we also run VMWare with Cisco UCS servers in order to offer unparalleled space and CPU. VMWare is recommended if you can pay for it, it's expensive. If you have a limited budget, we would recommend virtualizor.
VMware vSphere is highly reliable but bit expensive. If you are looking to offer budget solution to your customers then solusvm or Virtualizor is useful.
If are going to provide some control of the VPS to your customers, then you will have to think of panel that gives more features in it to the client like console access and template features.
The choice goes as follows:
SolusVM ( Requires Master separate and Slave separate if KVM or Xen has to be used)
OR
Virtualizor (no such requirement like the SolusVM.)
I would suggest to use Proxmox. It is a very mature software and best of all it is free. In case you encounter issues, you can always google it for people that encountered it before.