If you are getting the r9 290 now then pls dont the gtx 970 is out at much lower cost much(329$), more power efficient(145 watt TDP), amazing new features and much better performer than gtx 780 and r9 290.
I've always went with AMD but really right now Nvidia is the way to go , you might want to wait for the 390X which rumors say it will be liquid cooled and will have good price to performance but I am not really sure whether there's anything that can beat a 970 right now in a price to performance competition.
$349 for a MSI 970 or $400 or so for something that is 86% as fast, produces 47% more heat and power consumption, 4 times as much noise (49 vs 29 dbA), overclocks about 1/3 as much and gets less scaling when using dual cards.
If you are getting the r9 290 now then pls dont the gtx 970 is out at much lower cost much(329$), more power efficient(145 watt TDP), amazing new features and much better performer than gtx 780 and r9 290.
What about 256 vs 512 bit why does that not seem to matter?