In my opinion its going to be GPU. There's still lots of life left in the 4790k, and if you overclock it gets that much better. Based on what I have found, running it at 4.5 to 4.8ghz is a breeze and puts it on par with current gen chips. If you were to upgrade to even a 2070/2080 it would be a beast of a rig, unless you have the cash to do basically a full build and replace cpu/mobo/ram and cooler.... starting with a better gpu will yield you immediate results and when the time DOES come you can at lease have a solid gpu to pair with whatever new combo you choose.