Upgrade CPU or GPU?

Solution
Personally I would stretch for the GTX 1080 on June 10th. With the GTX 1080, you'll be able to do 1080p @ 144 Hz with either MSAA or Nvidia SDR. A $400 max budget plus you could gather at least $125 from selling your used EVGA GTX 960 (http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&LH_ItemCondition=3000&_nkw=evga%20gtx%20960&LH_Complete=1&LH_Sold=1&rt=nc&_trksid=p2045573.m1684). My guess is that the GTX 1080 (non-founders) will sell for a street price of $550. If that's more money than you're comfortable with then yes, purchase the 1070.

*** quote about Nvidia pricing of GTX 1080 and 1070 ***
"The GTX 1080 drops on May 27th with the GTX 1070 to follow on June 10th. The 1080 is priced at $599 while the 1070 will cost $379...
@xGrimalkin Your build in PCPartPicker is incomplete. For example, what is your storage? More importantly, what is your upgrade budget? What games were you hoping to play with the upgraded build? Were you planning on doing anything else with your computer, such as content creation? If so, what specific programs and activities? Also, do you live in the US and where do you plan to buy your components from?
 
@rcald2000 It's mostly for gaming, most of the time the latest games. I live in the US. I have a 144hz monitor, Samsung 840 EVO 250 GB SSD, along with a 1tb hdd. I usually shop through amazon or newegg also microcenter is my backup for w.e reason.

My budget is anywhere below 400$ and am only concerned with the cpu/gpu atm.
 
Personally I would stretch for the GTX 1080 on June 10th. With the GTX 1080, you'll be able to do 1080p @ 144 Hz with either MSAA or Nvidia SDR. A $400 max budget plus you could gather at least $125 from selling your used EVGA GTX 960 (http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&LH_ItemCondition=3000&_nkw=evga%20gtx%20960&LH_Complete=1&LH_Sold=1&rt=nc&_trksid=p2045573.m1684). My guess is that the GTX 1080 (non-founders) will sell for a street price of $550. If that's more money than you're comfortable with then yes, purchase the 1070.

*** quote about Nvidia pricing of GTX 1080 and 1070 ***
"The GTX 1080 drops on May 27th with the GTX 1070 to follow on June 10th. The 1080 is priced at $599 while the 1070 will cost $379. Founders editions of each GPU with new coolers which will cost $699 and $449, respectively."
 
Solution
/shakes head in disgust of self, sorry it was a long day at work and I completely missed it in the pcpartpicker link.

The only move you can make for the cpu is to an i7 which for gaming you most likely wont notice a difference, on the other hand if youre doing any encoding, streaming/recording game play, cad, or photoshop work then an i7 will help you out.