Which graphics card has best performance

I'd get the 770, since it's faster than the 7950 and even trades blows with the 7970. However, the 7950 has a good cooler on it, so if you are willing to OC, you could have a card that performs on par with a 7970.
 
Hey,
I heared that if you have 2 770's(via sli) than it can beat the GTX Titan. Or if you have the money, get the r9 290x as that may end up being the best single gpu graphics card out ther beating the titan and 780.
So my reccomendation is 2x 770's(SLI) or R9 290X.