The wonderful things about hypervisors is that there are so many frickin' ways you *could* do it.
For whatever it is worth, the current hypervisor recipe around here is:
A WIO based system (because the mainboard is shared between some 1U and 2U configurations)
Supermicro SC213A-R740W
Supermicro X10SRW
Intel E5-1650V3
64GB or 128GB DDR4 2133MHz
Supermicro
AOC-S3108L-H8IR 2GB LSI RAID Controller
plus the optional Supercap/TFM BTR-TFM8G-LSICVM02
That gives a very nice, high performance local I/O system. It's 8 ports of 12Gbps while the host chassis is 16 ports of 6Gbps but that isn't an issue for us. A M1015 optionally services the second 8 ports.
Two Intel X520-SR2 dual 10G SFP+ network (four interfaces total)
This is a great hypervisor platform which is fairly flexible. We've found that the balance of 6 cores to around 64-96GB of memory seems to suit the purpose around here; that probably explains why the quad core E3's with their 32GB were never an ideal fit.