Which should I upgrade first?

[souperzombie]

I should be getting some funds before next year but chances are I'll only be able to have enough to upgrade 1 part, most likely the gpu (MSI GTX 980 Ti Gold edition) or cpu (I7-6700k). Which should be the priority? I use my computer mostly for gaming and occasional video editing.
You can view a rough list of all my parts here.

 

[logainofhades]

Is your system not performing as you would like? To be honest your system is still pretty solid.