I need help picking a graphics card.

The r9 380 is by far the best card. In performance it is very similar to the r9 280x but i would say that a bit cheaper. If you are about to spend 200 dollars, you can even buy a r9 280x rather than a r9 270x. But being the 380 cheaper and the same in performance (and newer) go for it.
 
To be more specific the R9 380 is simply re-branded R9 285 that can hold 4GB GDDR5 video mem and is ONLY better if you were to purchase the 4GB GDDR5 version which you cannot afford.

At the same same price point of around 200$ R9 280x is more superior

FYI not sure what you're upgrading from but make sure you have enough wattage from your power supply to fuel the r9