younes-ea :
okay but what would you choose if you had the dissision
Well, if it were me, I would choose a really nice custom factory overclocked GTX 660, like the MSI Twin Frozr, Gigabyte Windforce, Asus DirectCU, or EVGA FTW+ Signature 2. And I would make that choice over the 7870 for these reasons:
1) Performance is the same. I discount the overclocking argument because I think the GTX 660 also overclocks very well, and the difference between the two when overclocked is still not going to be significant or noticeable when gaming.
2) The GTX 660 is cheaper.
3) The GTX 660 comes with a free game that looks like its going to be awesome.
4) The GTX 660 comes with good driver support, better SLI options, better 3D Vision, and offers some nifty technologies that the 7870 can't match, including: PhysX, Adaptive VSync, FXAA, TXAA, Geforce Experience, Shadowplay, etc.
But that's just me, and I'm not the one spending good cash on this.