Are you talking $190 US? I'd honestly steer well clear. For one thing, nVidia hardware gives a far smoother, more consistent framerate delivery, whereas AMD is using really up/down performance to average out to the same frames/second but without the same smoothness/responsiveness.
http://techreport.com/review/23981/radeon-hd-7950-vs-geforce-gtx-660-ti-revisited/3
It's well worth reading the article to the end. It's a new way of testing performance, to more accurately represent the 'smoothness' delivered by a card. Frames/second is a crude, oversimplified measure of performance that doesn't tell the whole story. We'll be seeing a lot more frame latency benchmarking moving forward.
The AMD fanboys were in uproar (over 200 comments on the article) about how testing on Windows 8 was to blame. So they re-ran the tests on Windows 7:
http://techreport.com/review/24022/does-the-radeon-hd-7950-stumble-in-windows-8/2 (first page is useful to understand the test methodology, benches start on page 2)
The conclusion:
"A moral victory in the borderline-meaningless FPS sweeps doesn't overcome the fact that
the Radeon HD 7950 has a persistent problem with high-latency frames across a range of test scenarios based on the latest games... If you just want bragging rights, by all means, choose the Radeon HD 7950. If you're looking for the friction-free fluidity that only comes from consistently quick frame delivery, though, our recommendation remains the GeForce GTX 660 Ti."
I know it's not the exact model you're looking at, but it's the same architecture/series so results are still applicable.
The other thing is Sapphire. Even if you're really determined to get a Radeon, don't get Sapphire. I've owned three, and all three died within 6 months after warranty expired. If you upgrade every two years anyway then I guess it doesn't matter, but I don't like being forced into buying a new card personally just because my Sapphire is built to die after a certain amount of use.