brand preference
That's what this is all about, some people will prefer to buy AMD and some prefer to buy Nvidia. I just wish people would quit acting like it some sort of rational "no-brainer" decision based on facts, rather than what it is, a personal preference.
software features
And this is why I would happily pay more for the Nvidia option. Maybe someone could refresh my memory, but as far as I can see AMD has nothing that can be considered a "software feature". On the other hand, Nvidia's suite of software exclusives are well-known, often useful, occasionally awesome, and unique in a forward-thinking way. Of course, if you are an AMD fan, then they're obviously all marketing gimmicks (see, no need to bother, I saved you the time and effort).