Which Graphics Card? 480/570/580

Im going to be buying 2 graphics cards soon for mining Ethereum which one should I get?
Asus (DUAL-RX480-O4G) $340 each
MSI Gaming X Radeon RX570 4GB $320 each
Gigabyte Radeon RX580 Gaming 4GB $340 each

Which would most likely be best ROI at stock and with modding?


Edit:
Also does Brand matter?
I chose the 480 as it is the only one I can get my hands on so can't change that.
But the MSI 570 I read online was good but I could get an Asus Expedition OC RX570 4gb or a Gigabyte Gaming Radeon RX570 4gb both for $20 cheaper
as for the 580 I can also get a Gigabyte AORUS RX580 for the same price, but for $50 more I can get the 8GB one, and I notice the 8GB has memory speed of 1000Mhz than the 4Gb so would it be worth it?

Also what are your thoughts on second hand graphics cards?
Thanks