I have 2 GTX1070 and 1 RX 580, I was mining on Nicehash but recently I'm mining BTCZ because I'm bored. I don't know if is better to buy more cards or just save it on bitcoin. Currently the ROIs are very high for GPUs. I live in Venezuela so, no costs on electricity, I'm making about 30$ monthly.
If you really do not have costs with electricity will always be profitable, in Brazil for example 30 $ do not pay the monthly costs with electricity. 0,23 $ KW/h.
![Angry](https://bitcointalk.org/Smileys/default/angry.gif)