Zotac make some of the best 'Amp' series factory (warranty) overclocked cards.
Frankly I think the Gigabyte ones are more esthetically designed, but the Zotac's are quite common cards for enthusiast websites to review as many of them have a pre-overclock and a warranty on it to boot.Read/Print this before making a decision
The GTX660 Ti does well against the Radeon HD 7950, even with only 75% the VRAM bus width. Thanks to higher clocked memory it has similar enough bandwidth and appears to make rather good use of it.http://www.hwcompare.com/13145/geforce-gtx-660-ti-vs-radeon-hd-7950/
I used to lean towards ATI far more than I have been recently, thanks to the NVIDIA GeForce GTX 600 series (not the GT series or lower):
- The other titles are likely to be more balanced, it's just depressing that AMD/ATI doesn't handle FP16 texels well.