Which version of PolicyPak do I purchase if I want to use it with my MDM service like Windows Intune, MobileIron, Airwatch or other MDM service?

The product you want is PolicyPak On-Prem, because PolicyPak On-Prem will utilize whatever transport you already have. In contrast, our PolicyPak Cloud product is for organizations which don’t have the need or desire to pay for an MDM service; our Policy Cloud service serves as the transport.