Got 6x470 (all sapphire Nitro 4GB, different mem chips though : 3 samsung, 2 elpida, 1 hynix) mining xmr @ ~ 4400 H/s. About 640W at the wall for the whole system so that's around 100W/card. No big difference between them in terms of hashing except for the hynix which is a bit lower (but it's the gpu on display).

Best choice regarding H/W and H/$ would be currently RX470 4G. However if you can find a 480 4GB at the same price, go for the 480