I love the amazing stories of trials and courage in the Old Testament, the miracles and wonders of the New Testament, but the Book of Mormon seems to embody all of those things in one. It's also more understandable for me, and I think that's why I read it more than the others.
I love the "plain and precious things" of the Book of Mormon...their lessons are numerous and astoundingly important. After all, the prophet Joseph Smith has said (something to the effect of) "Man will become closer to God by abiding by its (the Book of Mormon's) precepts than by any other book."
However, the deepness and complexity of the Pearl of Great Price is especially inspiring. Its name tells all - it truly is a pearl of great price. The book of Abraham, especially, is very overwhelming, with its information concerning intelligences, others of God's creations, and other things. I think it reaches out to me because I am always trying to find knowledge and it gives so much knowledge about many great things. I think reading the Pearl of Great Price is perhaps the best way to quickly grasp just how deep, complex, and everlasting God, his plans, and his works really are. I think it can bring one closer to the feeling of awe and weakness that Moses had after viewing all of God's creations.
I love the Book of Mormon best, because of the knowledge contained in it, and the simplicity of it makes understanding it easier to understand. I think the Book of Mormon must be the greatest missionary tool there is. I also love the New Testament because it contains so many teachings coming directly from the mouth of Jesus.