Like the others i would say it depends on your needs. The 7870 is the best single card performance in your price range. If your going for the most potential performance i would suggest 2x7770 as a possibility. It would give you the best overall performance for your money...but with much higher heat,power draw, and all the issues that may arise with CF or SLI setups. If your interested in the nvidia only perks like physx...ect the stock 660 would be your best bet. All though it is a slight notch down in performance from the 7870.
On a Side note IME when some one lists a budget range for part suggestions ie 2-250 it's usually meant literally. They want to spend only $200 to $250 out there pocket for a part right now. So why do these posts always get littered with "In your price range...after mir" suggestions? A $300 card with a $50 mir is not $250..it's still going to cost them out of pocket $300. Granted this one hasn't been bad, but i have seen some were literally ever suggestion (outside of weeks of waiting for a non guaranteed rebate check) is way out of the price range.
Amd Phenom 2 560(unlocked to 4 cores at 3.8ghz),xfx Radeon 6870 (ty again tr ^^ ),Cooler master haf case, 4gb of drr3 1600 ram, win7 ultimate 64bit