I really like J Scott's books, The Book on Flipping Houses in particular. Most real estate books, including the Bigger Pockets books, contain a ton of fluff. J Scott's books are straight to the point and extremely helpful. I wish he would write more.
It depends on where you are at with your investing and what you want to focus on for investing. If you haven't read any books yet, I would highly recommend:
How to Invest in Real Estate: The Ultimate Beginner's Guide to Getting Started - Brandon Turner
This helps you get a focus on your direction and a solid understanding about investing.