What pool is best for the D3?

I use Ant pool, pays a bit less BUT you get block rewards

How are you guys monitoring energy usage?  I have a kill-a-watt on my D3 (120v) currently, but I'm adding a 240v circuit and will be using a PDU when my 2nd D3 gets in, but I'm not sure if there is an energy monitor I can get that plugs into the PDU.  

So, are all of you that are quoting your wattage using 120v and using a kill-a-watt, or is anyone on 240v?  If so, how are you monitoring the wattage?
thanks