Well, since I only have four of the duos, I can't give *the* most accurate opinion..But I will say I fell in LOVE with India Song...I HAD to have it when I saw it, and I was not let down. The brown in India Song has got to be, hands down, 150% THE most beautiful rich, shimmering brown I've ever seen in an eyeshdow. I can't say I really use the accompanying color very much (it's a soft vanilla hi-light)..It doesn't seem to show up very much on me, but I'll bet on darker skin tones it's very nice. That being said, it's worth getting India Song just for the brown...
The other duo's I've been coveting (well, I'd like ALL of them, but the ones I want the most) are Mediteranee, Kalihari, Paris, and Bohemian Gold).
Anyway, in MY opinion, no matter WHAT you get, you simply cannot go wrong with NARS duos...Or, in fact NARS anything!! BTW, their cream shadows are to DIE for!