If you got the power supply for it, go with the gtx 970 costs like 350-400 and performs better than the 290x. But if you want amd then wait for the 300 series, personally i would avoid amd now, because many games are optimized for nvidia and amd driver updates wont happen very often like nvidia's.
ps: 4gb card for nvidia means 3.5gb, probably won't bother if you play on a single monitor at 1080p