As the title says I want to know which one you think is better. They are the same price and the MSI comes with farcry 3 (lol).
My other specs are:
CPU: i5 3570k
HDD: Seagate Barracuda 1tb
Case: Antec 200 V2 Atx
RAM: Corsair XMS3 2x4gb DDR3-1600mhz Desktop Memory
PSU: Silverstone SST-ST60F-ES Strider Essential 600W 80 Plus Certified Desktop PSU
OS: Windows 7 64 bit
P.S provide reasons for your answer and sources etc
7% improvement with 7870, in general.
Radeon HD 7870 153600 MB/sec
GeForce GTX 660 144192 MB/sec