PC gaming has evolved a lot during the last decade. Now we have powerful demanding games that can squeeze out the breath of your machine to death. Also there are machines that can play any game but not 'Everyone' can afford it. Majority of our gaming community lies between low to mid range cards. Everyone, before buying, searches for "Which card is better ?", "Which one should buy ?", "Which is cheaper ?", etc. In my opinion the "Best" graphics card is the balance between your 'Money' and 'Performance'. This is something kind of a never ending race. Both companies have name and fame in market. Over the time they both have produced cards providing better performance beating each other. In some games Nvidia performs better due to PhysX and CUDA while in others AMD performs better depending upon OpenGl configuration. Also people mostly like to combine Intel with Nvidia and AMD/ATI with AMD chips. But its always your choice whatever you like. One thing which I have noticed is that Nvidia provides latest driver updates frequently than AMD. While AMD is 'sometimes' cheaper for the same performance.
Conclusion: "Best" graphics card is the balance between your 'Money' and 'Performance'.
