An interesting article from Anandtech.
http://www.anandtech.com/show/5261/amd-radeon-hd-7970-review/12

Quote:
"As a result for the time being there will continue to be an interesting division in image quality between AMD and NVIDIA. AMD still maintains an advantage with anisotropic filtering thanks to their angle-independent algorithm, but NVIDIA will have better anti-aliasing options in DX10+ games (ed: and Minecraft). It’s an unusual status quo that apparently will be maintained for quite some time to come."
 

According to the article, the 7970 graphic improvements were fixes for problems in the 6900 series, like the AF shimmering. They did not add anything new to the image quality settings and are lagging behind Nvidia for AA capabilities. AMD may have a horsepower advantage in their top card for the next few weeks, but only because their "next gen" cards are competing with Nvidia cards that have been out for well over a year.