I'm not sure. Some books strike me more then others at various points in my life. For instance, the Gospel of John, was high on my list for a time and so was/is the book of Romans. I've been a fan of the Old Testament because the foundation to the Messiah was laid there, plus a number of books, like Daniel detail how the end-times will unfold.
If I were to be pinned down for a specific answer, I'd have to say the book of Revelation. Here we see God judging mankind in the tribulation, Satan defeated and Jesus rules the world in the millennial kingdom, only to see that we are still a sinful rebellious people and once again a multitude reject Jesus.
To that end, I've found the left-behind series to be a great series, while its fictional, there certainly some Biblical principals and gives you an image of how things could unfold.