Why did I love this book?
Most of the books on this list aren’t strictly about story structure but instead combine unique storytelling insights with innovative structural concepts. Topping the list in that regard is Film Crit Hulk’s Screenwriting 101. Equal parts writing guide and manifesto against overused storytelling techniques like 3-Act Structure and the Hero's Journey, his emotional approach to structuring stories is perhaps the most thought-provoking I’ve encountered. Unfortunately, the book is currently out-of-print, though I have heard that Hulk (a pseudonym, obviously) intends to release a second edition in the future. Fingers crossed.
This is currently out of print, but a new edition is expected soon.