For some reason I am compelled to jump in even though I don't have a ton of eyeshadows either. I just filled up my first palette and need to go get a second for 4 others I have to depot.
So far, I can definitely say that Humid and Shimmermoss are my most essential and beloved colored shadows. I am building neutrals more slowly, which is sort of silly and I'm not sure why, but I definitely feel that Signed, Sealed and Vanilla are essential. I haven't bought a black yet, but I am probably going to choose Typographic over Carbon; the texture, tone, and color payoff are way better in my eyes (I was playing with them extensively at a counter this past weekend, but am waiting till I get to the freestanding store to buy them in pans, of course
). For colors that sit on the borderline between neutral and colorful, I'm really liking Star Violet and Flip.
I'm really glad to see all the suggestions! I'm planning a shopping trip this weekend to the freestanding store and the neutrals on these lists, especially, will help me decide what I really need to get next.