Should I get the RX Vega 64 or GTX 1080?

[caffeinade]

The RX Vega 56 may be worth looking into, it has been said that it does outperform the GTX 1070 (though we should wait for proper benchmarks).
It should hopefully beat the 1070 and not draw an obscene amount of power.
Or the RX Vega Nano.