Which GPU to buy?

I'm building a new gaming PC at around the 900 dollar price point. I'm hoping to be able to play bf4 on high to ultra setting with 40 to 60 fps. The CPU i'm looking at is the amd FX-6300. The 3 cards i have in mind are the:

R9 270x 2g vs Radeon 7950 3g vs R9 280x 3g

which card would give me the best bang for my buck? Also bf4 recommends 3 gigabits of video ram, is it essential to my gaming experience to have the full 3 g's.

 

Thanks to anyone who replies.

I doubt you need 3 gigs of vram for bf4 at 1080p. Where are you from ? I'm asking because most of the people on this forum are from the US and you can get something better there with that budget of yours.

http://pcpartpicker.com/p/20OVx

I live in Canada 

 

best bang for the buck would be a FX8320 with 8gb ram and a 7950

This is a pretty solid build, follow the link and select canada in the top right, going with a 6 core may bring it under 900 CAD