My R9 280X is struggling to play, I'm only getting around 20-30FPS at ultra with 4x AA. I'm thinking if upgrading. What is the best card or xfire I can get that that can play the game at 60fps 1080p for the cheapest price?
It is better optimized for Nvidia cards and will continue having better driver support. I'd go with a single card solution like the Zotac GTX 780 http://www.amazon.com/gp/product/B00CWM95XC which you can get used for a very reasonable price.
Generally you will see stuttering with multiple GPU setups so it's not really recommended.
My R9 280X is struggling to play, I'm only getting around 20-30FPS at ultra with 4x AA. I'm thinking if upgrading. What is the best card or xfire I can get that that can play the game at 60fps 1080p for the cheapest price?
i have oc`ed my KFA2 GTX 760 and it plays watchdogs ultra like a dream (40-55 fps). i have temporal smaa on and 2gb textures. hope this helps.