Me and my friends have gonne for the Sapphire Nitro+ 8GB RX 480 as from our tests it is the most efficient card on the planet for mining in a budget up to 300 Euro per card. You cannot find a better deal as a GPU for mining at this price. I think it will continue to be so even after some time as the RX 500 series looks its only a re brand and just a bit higher clock speed, not much improvements.