What are the implications in the comparison of efficiency/functionality of the following Rigs:

A)  2 xfx R9 295X2 = ~$900 = ~1000W = 1120 SOLs ZEC, 120MHs ETH

B)  6 RX 470s = ~$1100 = ~880W = 1120 SOLs ZEC, 164MHs ETH

C)  5 R9 390 = ~$1200 = ~800W = 1250 SOLs ZEC, ____MHs ETH

I think all of details / presumptions are correct.  This would lead me to believe, as it stands, that C would be the most efficient option...correct?