for film, you want AMD, Games you want NVidia. Overall they're both very close in performance. I would say, if you have an Intel CPU, go for Nvidia. For an AMD CPU, go for the AMD. They tend to have special strings like AMD-V which require both CPU and GPU to get the full effect. Nvidia tends to work best with intel. Mainly because Intel chips work much better with CUDA and PhysX than AMD.
Long story short. pick based on emphasis.
try to go with a medium to high medium performance. AMD would be the 7850-7950. Nvidia 660ti-670FTW.