i would have chosen HDD but its only temporarly because my HDD is crap , in the future when ill get a better one my pick will be a GPU .so ill choose GPU
Hum.. My vote is Hard Drive because a few months ago by laptop fell on the floor and some of the sectors became damaged. Who knows when my data will hit one of the damaged sectors.
Honestly, my processor (i3) is ok with gaming, my ram is perfectly fine for gaming too, also my all other hardware are ok except my graphics card, so my vote goes for Graphics card