Both perform about the same, but when overclocked 970 gets ahead big time.
And for those ranting about the 3.5GB issue; stop, just shut up, the amount of ignorance you guys have is insane, you exclude the rest of the cards power over VRAM then you use it as an excuse to not buy it. I'm only going to say this once, 3.5GB is more the enough to VRAM for most games today, anymore is just unneeded unless you are doing something either then just games. I was pretty pissed when I heard about the false advertisement but I didn't care, it was performing more then I wanted it to.