Well done for stating the one thing that many people don't bother with when asking for help, if more people would just say this at the beginning of the threads so many arguments would never happen.
Anyway as for which card would be best for you, the 770 or the 7970 GHz ed are the two cards to look at, go read this review.
http://www.anandtech.com/show/6994/nvidia-geforce-gtx-770-review (don't worry its a recent review and done with new drivers)
and then you will see that they are so close to each other swinging this way and that depending on which game your playing.
Priceing is very similar on here, one thing to bear in mind is that certain AMD cards get a good bundle of games with them, listed here.
http://forums.overclockers.co.uk/showthread.php?t=18524382
Sorry not to be able to say get this card its better then the other, but in this case the two you have asked about are very very evenly matched, good luck with your choice.