choose the r9 280! is is slightly better than the 760 ! u can check anadntech.com for fps difference! with 280 u can have extra 1gb vram ! it will help you in future games!
now a days most of the games are amd optimized ! so u will be satisfied with the r9 280
with the r9 280 u will get 3-5 fps + in most of the games !