I preffer also the RX 470, if you get some old cards you maybe can tweak it to 570 / 580.
Here are some of the suggestions for Etherum Mining GPU.
Radeon R9 295X2
The Radeon R9 295X2 has by far the highest hash rate (46.0 MH/s) of the Ethereum GPUs on the market.
Radeon R9 HD 7990
Its hash rate is significantly lower at 36 MH/s.
Radeon RX 480
The Radeon RX 480 is most arguably the most economical in terms of cost and saving electricity. Its hash rate is 25.0 MH/s.
Radeon RX 470
A Radeon RX 470 has a modest hash rate of 24.0MH/s. Its power cost per day is exactly the same as the Radeon RX 480.
There ate several other Gpu eth miners, but i know these.