Which GPU should I get?

I'm currently building a rig with a friend and we're down to the following GPU options.
The prices are without VAT.

• ASUS Radeon RX 570 4GB - 185,00 €
  
• RADEON DUAL RX580 OC 8GB - 245,00 €
  
• Asus Radeon RX 480 DUAL 4GB GDDR5 - 195,00 €
  
• Asus Radeon RX 480 DUAL OC 4GB GDDR5 - 199,00 €
  
• MSI GTX 1060 6G OC GDDR5 - 198,00 €
  
• ASUS GTX 1070 DUAL OC 8GB GDDR5 PCIE3 - 379,00 €
  

Which one should I get? I plan on modding them to get the most hashing rate out of them