I have a amd fx 8350 for a cpu and currently a r9 270x and since its around christmas im looking to upgrade my gpu to either a r9 290x or a GTX 970 if it would bottleneck the CPU i also have a msi 970a-g46 as a motherboard.I will appreciate any answer.
GTX 970. Most big launch titles are more optimized for the 970 and the 970 gets similar benchmark results to the 290X when overclocked. 290X also get's hotter so 970 all the way. Better performance at a cheaper price
You can purchase either, the 8350 isn't going to restrict them.
They run very close in performance, one is a little faster in some games, the other is a little faster in others, the differences are small, though, usually no more than 6 FPS either way, not really a deal breaker.
Price may be more of an issue, AMD, or its retail partners have slashed the prices significantly while Nvidia has no reason to do so, I can pick up the superb Sapphire Tri_x R9 290X for the same as the less expensive GTX 970s' here in the UK.
Me, I'd get whichever one is bundled with the game/s you most would like, unless you're paying a great deal for electricity, in which case the GTX 970 is your weapon of choice.
As always, make sure the system case will accept the card you have in mind and that the installed PSU can feed it!
^ There is no great gulf between the R9 290X and the GTX 970, overall the cards perform much the same. The only game in the Toms article you linked to where the GTX 970 outperforms the R9 290X significantly is Watchdogs, which has been patched putting both cards much closer together: http://www.techpowerup.com/reviews/Colorful/iGame_GTX_970/ The cards in grey are stock parts BTW, overclocked versions will performs a bit better.
I DO agree on the power consumption, though, and if the OPs system is in a less than well ventilated case the AMD cards heat output may be a small issue, but I still think the two parts are too close together to say the GTX 970 as the only choice.
And yes, I have a GTX 970, bought before AMD dropped their prices and right at this moment, living here in the UK, and with prices as they are I'd almost certainly opt for the GTX 970 again, but only because FC4 is bundled with it and none of the games in the AMD bundle interest me.