If you're looking at simple specs then anything with an nVidia GTX 690 chipset overclocked at +1GHz and at least 4Gb of DDR5. At the time of writing this I believe this to be the fastest configuration for consumer (game) graphics processing. A few people currently offer this including ASUS, MSI
and EVGA although I'd recommend EVGA (I have both ASUS and EVGA parts and there is absolutely no difference in performance but I'm drawn to the EVGA more... no idea why)
I should also point out that I'm pretty bias towards nVidia over ATI as I use my GPU's for computing more than gaming and the developer support is much, much better.
---
http://sordie.co.uk
http://twitter.com/@SordieEO