@Jimmy_DA, there is no 8gb version of the R9 380. I think your thinking of the R9 390 which is 8gb VRAM.
@musab robbani, Any GPU you've listed (GTX 970/R9 380/R9 390) would be enough to play BF4, but considering if the PowerColor R9 390 8gb is on sale/cheap then I would go for that one. And yes the other posters are right, if you want to take advantage of DX12 you will want to upgrade to Windows 10 if what you posted is your current build. Its a free upgrade for Windows 7/8/8.1 users.