GTX 6xx vs HD 7xxx vs HD 6xxx

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I know that both amd's 7 series and nvidia's 6 series have their pros and cons but what i want to know is, for dolphin, what is the best? Wich one will work without having to do a bunch of stuff. I read about the 7xxx not working really well in 3d11 http://forums.dolphin-emu.org/showthread.php?tid=22966&highlight=7770 but did not find anything about the 6xx serie. I was leading toward the HD 7870 or the new GTX 660 (non ti) but if neither of these card are good for dolphin, i could also buy a 6950 and live with the disadvantages.