Two 1060's will have a better hash rate than one 1070 or one RX 580, except when dual mining. TDP on 1060's is good as well <100 W. If you can get two 1060's for the price of one 1070 or one RX 580, then get that.
Im think about DAG for 6Gig. somone says 6Gig is worst is he right?
Thanks
The Dag size is not even an issue for the foreseeable future. The Dag won't even reach 3 GB until early next year and 4GB until 2019.