Over the last month, daily mining profitability for ETH has more often than not exceeded ZEC. This has been a function of the rise in the price of ETH and a significant increase in ZEC mining difficulty (which far exceeded the relative increase in ETH difficulty). It is now more profitable to mine ETH and buy ZEC, than to mine directly.
Which does beg the question: Why has the ZEC network hashrate remained so high? I would have expected an equilibrium of sorts between ZEC and ETH profitability.
Data below for the equivalent of three GTX 1070 cards: 90 MH Ethash and 1.2 KSol Equihash.