for me, the best choice is sapphire nitro rx470 8gb. it's cheap, consume is very low. with zcash gpuz and hwinfo show 70W, with eth 100W, with anorak's ps mod bios.
Sapphire is my primary go-to brand, but the Nitro is overpriced for the performance on mining. I just wish their blower-type RX 470 model wasn't a backplate design.