When considering the products to purchase for your flight training or your aviation maintenance technician training, there are really only two good choices. The first are Jeppesen products, and the second Gleim Aviation products. And for me the choices are very simple.
The Jeppesen manuals are hardcover, fully illustrated in color and will last forever with care in your library. For example, the Jeppesen Private Pilot Manual has 620 pages and weighs over 5 (five) pounds! The Gleim Aviation manuals are softcover, illustrated in black and white on recycled paper, and will yellow and fade with age - not good if you are building an aviation library. Here the Private Pilot Manual has 346 pages and weighs a mere 1# 6oz (one pound six ounces)!