I would say that virtualizor looks great for the end users - and that's the most important aspect when running a business, how it appears to the end user, it also integrates well into WHMCS, and IIRC, Blesta as well.
There are many options for SolusVM like Achipel, VM Manager;
I would prefer Virtualizor
Virtualizor is a powerful web based VPS Control Panel. It supports OpenVZ, Xen PV, Xen HVM, XenServer and Linux KVM virtualization.