GTX 1070 is a good choice and would def stomp any title @1080p w/every setting imaginable to include MODS enabled (if you are into that) without breaking a sweat. If you ever upgraded to 1440p, you'd be set with that GTX 1070 as well.
The GTX 1060 is definitely playable at 1440p, but not on the level/settings enabled like the GTX 1070 will allow and of course, budget comes into play when comparing the two.
If you plan on staying with 1080p for several years, save your money and roll with the GTX 1060 as it's a bargain for what it does at that rez and if you decide to upscale into 1440p later, it will do you fine until you upgrade GPUs again. By then, the current series will be outdated and OUTGUNNED.