Is your difficulty on deciding which graphics card to get comes from a price standpoint? If not, you should ask yourself what you want to accomplish with the graphics card (gaming/graphics rendering/etc.), plus each graphics card offer different features. Shadowplay/physX for nvidia and mantle/trueAudio for amd. That should be a good start :)
If you have any interest in any sort of gameplay-recording or streaming, I'd go with the 760. Its ShadowPlay feature lets you save prerecorded footage up to 20 minutes and also can stream to Twitch all with little performance loss. I just upgraded to a 770 and absolutely love it.