Picking a GPU

[Mentions]

Hi there so I'm looking to upgrade my GPU but extremely conflicted with which GPU to use. I currently have a
i7 3770k CPU
Sabertooth z77
750w PS
16gb 1600
256gb vertex 3 ssd
3 tb seagate hdd

I'm looking to play battlefield 3, crysis 3, Starcraft, WoW, and battlefield 4(when it comes out) on max and stream my games online as well. My budget is 500(600 topss if need be) CAD any ideas/advice would be extremely helpful thanks!

 

[peterisluego]

GTX 680 or Radeon 7970. If you want, you could go with two Radeon 7950s in crossfire

 

[Mentions]

I've heard that crossfire doesn't wanna work with some certain games do you think that would be a problem? And would the 680 run those games on ultra while streaming??