The Radeon 7970 is on par with a GTX 680 (if not better in some games). In this case, the 7970 is better than the 670, easily. Consider though, that it does consume a bit more power than the 600 series cards. I can't tell you about the models you've mentioned in specific. But I recommend you look around a bit, and get something with nice cooling so you can overclock and get even more bang for you buck.