You want a work station card, not a gaming card.
But actually, Photoshop does not need much of a video card. A inexpensive low end work station card, or a mid range gaming card is all you need. For this I would also suggest you stay with nVidia.
What Photoshop needs is a fast processor, and the more cores the better. Photoshop is not a true multithreaded program, but it will use as many CPU cores as there are available to render an image. If you are working with large files, this is really important. Lots of memory, a fast quad core, and a fast hard drive will bring more delight here than dropping a wad on a video card.