I would say it depends on monitor size, for 1440p and under go with the 970. For 4k+ go with the 290x.
Even then it's slightly debatable unless you upgrade to the 8GB version of a 290X.
And in all actuality if your going for 4k I would recommend 970 SLI, 980 SLI, 295x2... something along those lines just to have decent performance. More then likely the poster is going to be better off with the 970.