Nvidia and CUDA all the way, especially with higher end editing software like those from Adobe. I have tested GeForces, Radeons, Fire Pros and Quadros. The GeForces always came out on top. The more CUDA cores, the faster it will go (as long as you use the 400 or 500 series cards, not the 600 series (even though it has many more CUDA cores, it is not nearly as fast in software).
Yeah. It seems NvIDIA did something to their 600 series cards. It seems they want to make a place for their Quadro series cards. Quadro used for what your suggesting, and Geforce for gaming. (Geforces origianl purpose)