I think a lot of this depends on your budget, I mean personally the best value in GPU right now is the 980TI but most gamers aren't ready to throw down 650-ish on a GPU.
AMD really missed an opportunity to increase their market share. People who just bought a 960-970-980 card aren't going to dump them in favor of the 390x, and even if the Fury card does motivate some of those 900-class card owners to sell that will only flood the used card market with Nvidia product, so someone with a 200 dollar card budget might be able to pick up a used 970 and save a few bucks vs the 390x or Fury.
AMD is in the unenviable position of always playing catchup to Nvidia, Nvidia comes out with a 900-class card, then a year later AMD comes out with their 900-class card. Always after people have invested in the Nvidia model do the discounted AMD equivalents come out and seemingly always with a power/heat tradeoff.
EDIT: ok now that I'm done with that rant, if those are my only choices, the 970 would be my choice, but if you can hold out and save up a few more dollars a 980 would be best if only because since the 980TI came out the price on the 980 has gone down a bit making it a little bit of a stretch beyond the 970 budget but not unreasonably so.