What's your preferred price point on your graphics card? Any card you choose would probably be fine with your 6300 because the 6300 wouldn't bottleneck it that much if at all.
The R9 270x is probably your best bet for that amount of money...that is assuming your power supply is big enough to handle it. If it's not see if it's powerful enough for the 750 Ti. That card will take very little power in comparision.
I need a good Graphics Card to go with my FX 6300, Gigabyte GA 990 FXA UD3 Motherboard for about $160, any advise would be appreciated - Thanks
For $160 your two best choices would be the GTX 750ti ($150) or the r7 265 ($150-$170). For $160 those are you're best choices, and the r7 265 is faster than the 750ti so I'd go with that one. And if you are willing to spend $40 more then go with the r9 270x. Hope this helped!