Better is a relative word. Performance-wise, they will exchange punches depending on the game. Power-wise, the GTX 970 will use less than half what the R9-290X does for basically the same results. http://www.anandtech.com/bench/product/1355?vs=1059
the r9 290x and the 970 are about the same, one is faster in some games, and the other is faster in other games, but the 970 is better than the 290 non X.