Well as you mentioned the "best" graphics card for high resolution gaming is the GTX 780ti, if you have $750 to spend that is. You can drop about $200 off that price for the GTX 780, which is still a beast of a card.
The r9 290 will run you about $550, give or take a few dollars but it seems like AMDs board partners are being rather slow to release their own cooling solutions. There are a couple of them about there but they are kind of pricey.
Typically I'm a huge fan of AMDs graphics cards, but personally I would go with NVIDIA this time around. The GTX 780 runs cooler, quieter and uses less power.