I literally just finished Cuckoo Song tonight. I think, having read all of her books except Verdigris Deep, that this book feels like a level up in technique in some ways, but Fly By Night will always be my favorite, because MOSCA MYE (closely followed by Twilight Robbery), but I was also amazed at Gullstruck Island. A Face Like Glass is great too. I don't know. It's hard to decide. I can't wait for The Lie Tree.