When formulating this list, there were many runners up which failed to be either internalized into my character or to be truly great. However, each of these I would heartily recommend to anyone.
Ecclesiastes
As a yet unspoken rule, I did not allow scripture to place in my list as the nature of the Bible transcends the purpose of my endeavor. However, I have long experienced a special connection with Ecclesiastes. It is a divisive book, and I think this primarily a result of its subject matter, meaninglessness. Some might be shocked to learn that there is a book in the Bible which declares that all of life, and everything anyone will ever do, is meaningless. Some read this and are frustrated, and yet I am frustrated until I remember that all is vanity.