AMD has been having problems with frame latency. They have tried to address the issue in recent driver updates. It's worth it to check out these articles:
http://techreport.com/review/24218/a-driver-update-to-reduce-radeon-frame-times/5
http://techreport.com/news/24136/driver-software-to-be-tweaked-to-reduce-radeon-frame-latencies-in-series-of-updates
http://techreport.com/review/23981/radeon-hd-7950-vs-geforce-gtx-660-ti-revisited
Both cards are pretty much toe to toe, with some games better optimized for the GTX 660 Ti and some games better optimized for the Radeon HD 7950 so it'll depend on the games you play. I'd recommend looking up some benchmarks on the specific games you play, but overall either way is a good choice and either way you should be able to play all of today's games at high/ultra settings at 1080p.I'd actually recommend Sapphire's HD 7950 Vapor-X comes with a large dual-fan cooler that uses the company's famous vapor-chamber technology. On the Vapor-X you will also find a "Lethal Boost" button which switches to a second BIOS with higher clock speeds. With this BIOS, clocks are increased to 950 MHz GPU and 1250 MHz memory.I bought one for my son and hes had no issues i can't speak for others though.If you prefer NV the GTX 660 Ti provides top notch performance with extremely high efficiency, so you’re guaranteed to be getting a ton of performance without a lot of energy or creating a lot of heat either. With MSI’s Power Edition GTX 660 Ti, you’re also getting MSI’s legendary Twin Frozr IV cooler, which will provide excellent cooling along with MSI’s triple overvoltage design that allows you to do a little overclocking to improve performance if you’re feeling adventurous.