Hugs, Ink. Here's some pragmatic advice. Whatever structure you choose, when you sell this book, your editor may well have you rewrite it to fit another order. So keep the outlines and choose the structure that will get your agent to put it on sub for you. You can't sell it until you sub it.
The hypocrisy! The irony! I came into work today (at a business school) and I was given a t-shirt that I must wear to a team meeting. So my body is now emblazoned with an infographic boasting about all our C-level alumni in various industries, and by far the largest sector is finance.