Have you ever considered the GTX 770 ? It's has similar performance to the R9 280x , but comes with 3 free games. Check to see if your retailer is particpating in the campaign first.
The HD 7970 is the cheapest of the 3 , and also comes with 3 free games. I prefer Nvidia's bundle
free games
http://www.amd4u.com/radeonrewards/
the HD 7970 qualifies for the gold class reward