Everything I've heard from Hardcore History has been excellent. Blueprint for Armageddon is a masterpiece. My personal favorite is Kings of Kings. It's not really considered among his best work, but I love the subject matter.
Blueprint is insane, when you finally understand most of today's issues (and all of WWII) Stem from that war. A war started by sheer luck or destiny. A war were idiocy seem to rule, and people thought 18th and 19th century tactics would work in a 20th century fight.
