The 6 motif magic necklace is unique and surprisingly, goes well with a lot of necklines. I just got mine and am really loving it. It just gives a very interesting visual to the outfit, imo. There a few threads in this forum on the 6 motif where you can get good info. I don't own the 20 motif but I join my 5 motif to my 10 motif, which is similar to the 20 motif in style. That is the perfect length for me (I am 163 cm). I feel the 20 motif will hit me too low. I agree with the suggestion to try on both in the boutique. Personally, I would go for the 6 motif in MOP YG-it is such a lovely piece.