It is clear from this breakdown that the AMD Radeon R9 290X is the better value in terms of performance by a long shot. It is $150 cheaper than the GeForce GTX 780 Ti, but delivers the same gameplay experience and very near the same framerate performance. A performance difference that makes little or no real difference. The $150 price difference is a much larger difference than the performance difference.
Looks like in terms of most important metrics, AMD's R9-290X and 290 is both a better value in terms of gameplay performance and with 512bit 4GB memory, much better when single/xfired at very high resolutions.
For most people the price and price/performance is a show stopper, but the 3GB vram is a brick wall in terms of even short term future proofing and high resolution gaming.