Wow so many wonderful icons! In general I really like how all the colorings turned out. And my overall favorite grid is the gritty/matte one.

As for my individual favorites: 1 (love the crop and the shade of pastel lilac), 5 (maybe my overall favorite; I love the crop, warm tone, contrast and the general feeling), 6 (so simple yet so pretty and interesting), 15 (lovely warm reddish lighting and contrast) :D

Also you were very clever to find a way to measure brightness (I might have tried it too for the saturation, but not too strictly lol).