SolusVM and Virtualizor was only working on Centos 6/7, but Virtualizor can now be installed on Ubuntu 16.04 and even on top of Proxmox VE.
In my opinion, with the last Proxmox v5.0 release, build on Debian 9 Stretch, with awesome features like live migration, Debian/Ubuntu will probably more popular than Centos.
When Openstack is already running on Ubuntu, and with all issues with Centos 7 and KVM due to some packages (require to reboot host almost each 24h).
I prefer KVM and by many providers do you get SolusVM as default by ordering your VPS/Dedicated servers. I use self CloudLinux 7.3 and 6.9 which fits for me the best solution. But SolusVM is an idea to use but I always prefer CloudLinux.
As KVM core is maintained by Redhat (not really, but basically), its always best to use a Redhat based system. Centos 7 is much faster then Centos 6 on the same hardware, when using modern CPUs and chipset.
SolusVM is not the same platform function as KVM or CloudLinux, however if you need to choose in to VPS then you can better use CentOS 7 or KVM. Because CentOS does not support everything. But @David, you putting a thread in Dedicated servers and then you can choose CentOS, KVM and CloudLinux, you wanted to know what the best choice is. So my answer on it is CloudLinux, however it's one that I always used in the past 5 years. You can give a shot to CentOS or KVM.