These are not numbered for a reason. All of these books are important for various reasons and none are more important than the others. I am listing ALL the books that have had impact on my financial life. Please do not confuse listing order with preference, I am merely adding titles as I pull them off my Kindle.
Rich Dad Poor Dad - This book is instrumental in changing your mindset about money and the importance of passive income in life. I can not begin to talk about how much it has shaped many of my money decisions in life. This book will help change your mindset and your future!
The Total Money Makeover - Dave Ramsey was instrumental in getting me out of debt and understanding why I didn't want to live like everyone else. He changed my way of looking at things and is still helping me get to where I want to be. While we don't agree on everything, he is still an incredible leader of people.
Unshakeable - Tony Robbins will blow your mind if you let him, and I suggest you do. This is a great book that has 2 specific chapters of "gold" as far as I am concerned. His two chapters focused on mindset make this book worth the price alone. If you want to get ahead YOU MUST change your thought process.