Hi,
Just FYI but the GTX970 comes with TWO free games whereas the GTX960 comes with ONE. I'd also recommend at least 2GB of VRAM so I'd compare a GTX960 4GB vs GTX970 4GB.
960 - Witcher 3
970 - Witcher 3 and Batman Arkham Knight
The GTX970 is 50% faster than a GTX960 (averaged over 20 games at Techpowerup).
*Depending on total budget, it might be worth while considering an i5-4590 instead if that means you can upgrade to a GTX970 such as the Asus DC2 model or EVGA ACX2 SC model (see pcpartpicker). It only saves about $25 so only if the budget is very tight. $190 vs $215 though you may find sales.
If the GTX970 is still out of reach then the GTX960 4GB (not 2GB) would be my recommendation. Again though, the GTX970 has the extra...