I'm not a "fanboy" of any brand.. I've just gone through experience with building more systems than I remember for my own use and for clients, be it business or pleasure clientele.
The bottom line is Nvidia (and Intel) are just hands down worth the extra money in the long run. I've done plenty of AMD/ATI builds and Intel/Nvidia builds.. and even mixed them. I was ALWAYS disappointed in AMD/ATI whether it be noise, driver issues, bios issues, compatibility issues, etc. With Nvidia I've yet to be disappointed. Nvidia simply , for me and my experiences, has won every single time.
Even if AMD has a card out that is 10% faster, I'll still pick Nvidia.. whatever you buy today that may be the "best" will NOT be the best in 6 months or so.. it will always be that way. Some people use that as reason to buy a considerably cheaper card/hardware. I think the "wisest" decision is to buy the model of card JUST under the latest and greatest.
IE: If the 780 is $500 ,, and the 770 is $320-330 or so.. Go with the 770, the improvements just aren't worth $150+ . That said, I'm in the middle of a complete new build for myself, where I research for weeks on every detail of every component down to the case and psu.. and I'm about 80% sure I will pull the trigger on a $499 Nvidia 780 this time.
Why?
Most of the time I wouldn't, I would definitely get the 770 for $300-350... but, the 780 is not just a "faster" card.. It has a 384bit BUS,.. while the 770 is running on 256bit.. The 780 has 2880 (or 2304 in some models) CUDA cores.. It's a BIG gap and different technology.
I really wish the 770 was running on a 384Bit BUS and that would be enough to save me from going with a 500 dollar video card.
I am looking at the AMD cards and they look great, as they always do , due to price for performance in contrast to Nvidia -- but I remember the dozens of AMD cards I've purchased in the past that have disappointed... and when I get done with a build I don't want some annoyance or disappointment to bug me from day 1..
I could always wait 6 months and the prices would fall.. but at that point I can wait another 6 months.. then the 800 series is out.. but that just keeps going.
I run in my own system a 560Ti Fermi (IIRC) .. still a great card, but when doing a completely new build I want something that is 2-3 year minimum future proof for gaming.. I've come to really like Silent hardware,.. and Nvidia brings that to the table as well.
For all who go with AMD cards.. great, they are well made hardware and for the money almost always the best bang for the buck, you can't argue with that.
I'm just glad AMD stayed in the game and can still compete with Nvidia, and to a lesser extent Intel lately.. or prices would really be extreme.