Both will likely work. I would take the 3770k.
Okay you have Gen 2... But which? If You're running a k chip, it may just be worth to overclock, the 3rd gen is slightly faster but your chip runs cooler.
Which GPU do you have? Because if you have an i5-2500k... Upgrading to 3rd Gen i7 is really not going to make a world of difference, they are very similar in performance. I think you will see a much greater difference in GPU change