Either or are great cards. Personally, I find Nvidia's driver support better than AMD's.
If it was me I would go for the Gigabyte Gtx 670 OC, super quiet and keeps the card quite cool. It gives you near gtx 680 performance but it's $200 cheaper. NCIX has a deal on them for 369.00
http://ncix.com/products/?sku=71107&promoid=1043