I have the Sapphire Pulse Vega 56 and its a great card. Combine it with Global Wattman for overclocking and it runs great. I get about 1500mhz and doesnt go over 65-70c on load. Im only thinking of changing where I've bought a G-Sync monitor but ill see how it goes first.
Heat added thanks for the share! Got my GTX 970 more than 4 years ago for 280 and replacing it with this 4 years later and I could even trade in the old card with CEX for 60 pounds meaning its just over 210! Hopefully at least another 4 years with this card! :)
Super tough to answer, the Vega has more potential if you like to tinker.
This or sapphire pulse vega 56 for 248?
The extra 2GB of RAM on the 1070 cards means some games are better on the 1070. There's no definitive X is always better than Y.