If you're just about gaming then the AMD is the best... And they are Cheap also... You can get more than NVidia in the same price in AMD...
But, If you're about to do other stuff like Video Editing, Rendering, etc... then It's the Nvidia... That support all these functions better than AMD...
Also there driver support is also very good...
So, If your gonna use Video Editing, Rendering, etc... Stuff like that I would suggest you within $250 a GTX 750Ti or 760...