I've read "Modern Day Gunslinger" and enjoyed it but didn't feel like I took much away from it that I hadn't heard before in other books on the subject. That said, I'm a fan of Massad Ayoob's books and I had read his 2011 "Combat Shooting" before MDG. His "Gun Digest Book of Concealed Carry" is also excellent if you plan to pursue the daily carry of a firearm.
If you want to get heavy in to no-holds-barred tactics books, you can check out Gabriel Suarez. He has several books that fit that bill - "Tactical Pistol" and the "Tactical Advantage" overlap but are both helpful.
If you want to look at psychological, legal and emotional aspects of personal defense, I highly recommend "Facing Violence" by Rory Miller an "On Killing" by Lt. Col. Dave Grossman. Best of luck!