There are about 5 games in the world that run DX12 and/or Vulkan. There are hundreds, if not thousands of games that run DX11 and older, or Open GL.
Newegg is having a "sales event" right now, and I'm seeing a lot of GTX1060's right around the $240-$260 mark. Much better than the $400 GTX1060's I was seeing two weeks ago. The cheapest 390x is still around $450, and the RX480's are right around the $250-260 range as well.
My vote goes to a GTX1060 if you're going to buy one in the next 3-4 days.