Avoid Gleim for the ATP written! I purchased their study guide last fall right off the website. I knew the book up and down. I even checked the website for any updates to the current questions. When I took the test, there were at least 15 questions that I had never seen before! Most were ADM and CRM type questions that were not in the guide. I made my best guess but got most of them incorrect. I passed, but the score did not reflect the study effort I put into it.

When I called Gleim, they told me that the FAA has started to slip some of the new question bank into the current test and that they were aware of the situation.

I've always used Gleim for past test prep and my CFI renewal and been happy with the product. Most of my fellow mil guys have gone Sheppard Air and had good results. I wish I hadn't gone the cheap route.