Other two? I believe, the "rlshosting" user has provided only two options i.e. Virtualizor & SolusVM. Since, solusvm is integrated in the WHMCS and widely used, I believe it is best.
Prefrence goes to SolusVM but that does not mean that the other two are not good :)
SolusVM is best when u can easily make vps reseller from them
SolusVM- It has tight integration with WHMCS.