I agree on the 1070 ti (or just 1070s).  Mining ethereum I get a stable 31-32 Mh/s drawing only 95-110watts with the 1070s.  Take into account the power consumption of cards and the PSU you will be using when you plan out your rig.  When I tested AMDs they were drawing a lot more power (forgot how much off hand). 

Its a balance of how many cards your motherboard can support, your PSU and what cards you can get.