Gtx 960 or 970?

Solution
Using BF4 as a baseline:
Stock 960 performs at 65FPS on 900p
Stock 970 performs at 77FPS on 1080p.

If you OC well enough, you can close that gap or even match the FPS.
900p vs 1080p.

Don't you think comparing FPS in different resolutions is quite misleading?

https://www.youtube.com/watch?v=uK0VAPwrnmM

The gap between 960 vs 970 if far more wider then between 970 vs 980.
There is no way you can get even close to the performance of 970 even after heavy OC

http://www.guru3d.com/articles_pages/gigabyte_geforce_gtx_960_windforce_2x_review,21.html

On the other hand nVidia priced this GPU quite well, ~200$ for 960 vs ~320$ for 970....
You pay 160% but you wont get 160% more performance, thus 960 seems to be more cost effective.