If the R9 290 was relabeled to the GTX 960 Ti with all of its current pricing, this would be a no brainer. We'd choose the GTX 960 Ti over the GTX 960. That extra $50 spent is so much performance gained you'd be insane to pass it up, we'd tell potential buyers on this forum.
But because it's AMD vs Nvidia, now personal reasons come into play.
And that R9 290 will overwhelm all but the best 500W PSUs. Anyone with an OEM system from a major mfr need not apply.
So right off the bat 90% of PCs are ruled out without replacing the PSU, and that's assuming all the DIY builds can handle it - many cannot.
And if your PC can handle it, it'll sound like a small vaccuum cleaner.
R9 290 power :
And for those that don't quite know how paying for power works -
An R9 290 puts out about 150W MORE than a 960. That 150W comes out in the form of heat, so not only do you power 150W more, you have to cool 150W more.
BTUs required to cool this 150W is 3.41BTU/W X 150W/Hr = 512 BTU
Energy Required Per Hour = 512 BTUs .293 watts/btu = 151W. Of course the AC will also have power loss, and not everyone has high efficiency AC.
You can go here to see what it costs you per year :
http://www.rapidtables.com/calc/electric/electricity-calculator.htm
At .15 per kwh @ 300W/hr, I calculate $65 per year *more* to run an R9 290 vs the 960. Edit: this is at 4 hours / day average use.
So at the end of your first year of ownership that 'cheap' $250 R9 290 is suddenly a $315 R9 290. And it will just keep giving (or should I say taking) every year.
R9 290 noise (for one of the cheaper ones at Newegg) - Idle, gaming open-air testbed, gaming closed case :
HIS R9 290X IceQ X² Turbo
31.2 dB(A)
46.2 dB(A)
48.8 dB(A)
The MIS Gaming 960 in fully stressed / loaded state was 38db.
If you don't understand the db system, 48db is literally twice as loud as 38db.
60 dBA Noisy lawn mower at 10 m distance
50 dBA Refrigerator at 1 m distance; bird twitter outside at 15 m distance
45 dBA Noise of normal living; talking or radio in the background
40 dBA Distraction when learning or when concentration is needed
35 dBA Very quiet room fan at low speed at 1 m distance
25 dBA Sound of breathing at 1 m distance
0 dBA Auditory threshold