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!