Petar Raickovic :
I suggest you to wait for new Gpu lines AMD/Polaris or Nvidia Pascal.... Anyway No bottleneck in Dx12 ... and you 6 Cores gonna do nice job... not like in Dx11 when 2 or 3 cores are on 100% others are on party drinking bear.... If u must buy i suggest 380 it's 180$ or 380x 220$ sinc 900 series are Crap in dx12
Theoretically no bottleneck in DX12. They still have to do optimize the coding. Also, no indication of how many titles will be well optimized within the next two years.
But even if the FPS is lower than it could be with a faster CPU you can still have a great experience if you tweak properly.
*For reference, a stock GTX750Ti is about 20% faster than an R9-260X.
https://www.techpowerup.com/reviews/ASUS/R9_380X_Strix/23.html
Do note that games VARY a lot in how much the CPU is a bottleneck. Thus, your FPS will be lower than average than above, but some games will be close (like Tomb Raider which tends to have lower CPU requirement than most modern titles).
**Here's a good card for $180 (R9-380):
http://pcpartpicker.com/part/sapphire-video-card-100384nt4goc2l
(approx 2X R9-260X and also 4GB video memory to future proof)
NVidia has better DX11 drivers so I wanted to recommend them, but on the other hand they aren't as competitive at this price point. And while there's other things I prefer about NVidia, they don't have hardware ASync Compute which may be a big deal for DX12 games.
Unfortunately we don't have enough information on ASync Compute yet in terms of most games (the AoS game for example is a worst-case scenario likely.)
Also, as I said we have new GPU's coming. The ONLY one that's likely in your price range is Polaris 11. It should be a little better value than the R9-380. Possibly slightly cheaper while being slightly faster.
Summary:
The R9-380 is about the only card I can recommend for the reasons above. Pros and Cons to NVidia vs AMD.
Performance should average about 2X that of the R9-260X depending on the game (mainly depending on CPU load). That's based on the average of 20 games at Techpowerup.