have a look at the figures, they might help:
if electricity cost is a concern: (i.e. 24/7 use for months, years) NVidia
gtx 960 ... WPA2 at around 42 kH/s, details http://hashcat6.rssing.com/chan-14131099/all_p73.html
gtx 970 ... WPA2 at around 168 kH/s, details https://gist.github.com/joshuaskorich/76...49acb69387
gtx 980 ... WPA2 at around 213 kH/s, details https://gist.github.com/epixoip/abd64f1af800013abb1f ... at around 165W
if electricity cost is not a concern, short time use or you simply want maximum bang for the investment: AMD
hd7970 == r9 280x ... around 160 kH/s for WPA2 ..... (price paid ~170 eur) at around 250 W (afair)
r9 290x ... around WPA2 200 kH/s as far as i remember (price paid ~200 eur) at around 300 W (afair)
hd7990 ... around 320 kH/s for WPA2, i've measured something around 500 W (price paid ~300 eur)
(all prices for second hand purchase)
so AMD cards are offering more bang for the buck (which also attracted me very much in the beginning), but you will pay more for electricity in long term. - so it probably depends on your usecase, how much the card is going to run. ...
if electricity cost is a concern: (i.e. 24/7 use for months, years) NVidia
gtx 960 ... WPA2 at around 42 kH/s, details http://hashcat6.rssing.com/chan-14131099/all_p73.html
gtx 970 ... WPA2 at around 168 kH/s, details https://gist.github.com/joshuaskorich/76...49acb69387
gtx 980 ... WPA2 at around 213 kH/s, details https://gist.github.com/epixoip/abd64f1af800013abb1f ... at around 165W
if electricity cost is not a concern, short time use or you simply want maximum bang for the investment: AMD
hd7970 == r9 280x ... around 160 kH/s for WPA2 ..... (price paid ~170 eur) at around 250 W (afair)
r9 290x ... around WPA2 200 kH/s as far as i remember (price paid ~200 eur) at around 300 W (afair)
hd7990 ... around 320 kH/s for WPA2, i've measured something around 500 W (price paid ~300 eur)
(all prices for second hand purchase)
so AMD cards are offering more bang for the buck (which also attracted me very much in the beginning), but you will pay more for electricity in long term. - so it probably depends on your usecase, how much the card is going to run. ...