EVC is used to ensure that VMs run pn a common CPU instruction set, so what you want to select is the lowest supported level for both CPU models. In this ase it's Broadwell due to the E5 processor.
Note that you cannot change (lower) the EVC level, if you have VMs that were powered on on the Skylake CPU, i.e. with a newer instruction set that the E5 processor supports.
André
