What do you want to play/do? Do you have a budget? something in the mid-range. I have two G3258s; the same frequency, but overclockable. I run one with a GTX 750ti, and the other, when I'm not using just the iGPU, uses a GTX 970, which it is not capable of driving to the max in some games.
Some games are CPU intensive, there the G3250 will hold you back, others are very GPU intensive, there the GTX970 will be fine.
I'm assuming that you have a moderate to low-budget system, so something like the GTX960 would be a good middle.
Specific games perform differently on Radeon and NVidia GPU chip sets, and you need a PSU capable of running the whole system. What do you have?