GTX 1060 would be a significant upgrade over a 760 and would be perfectly functional at 1080p.
The question of whether to aim higher depends on whether you want to play past 1080p and higher refresh rates. If you game exclusively at 1080p, you'll be fine with a 1060; if you want to turn up the resolution and details, then a 1070 might be more up your alley.
And if you plan to go 4K, then 1080 or Titan X is pretty much the only way to go