All of scripture- from Genesis to Haggai and Matthew to Philemon- is holy inspired and valuable for teaching. I will say, in my humble opinion, that the Gospel of John is the most important New Testament book for student ministers to teach to postmodern teens.
In the following paper, The Gospel of John as Priority Text for Postmodern Teens, I write about John's concept of eternal life, compared to that of Matthew, Mark, and Luke. In the Synoptic Gospels, content about eternal life almost always pertains to that which believers inherit when they die and go to heaven. John's Gospel, though, portrays eternal life as something one can receive and experience immediately upon entering into relationship with Jesus.
John, much like postmodern youth ministers, primarily wrote to a culture focused on their experience in this life. Greek philosophy and religion emphasized the fullest life on this earth, with little consideration of the age to come. Consequently, John accentuates the benefits one receives in this life through relationship with Jesus. A good example of this mentality is the well-known verse, John 10:10, where Jesus says, "The thief comes to rob, kill, and destroy. I have come that you may life, and have it to the full." Jesus was not talking about heaven; he was talking about here and now. (To be clear, we are not talking about health, wealth, and prosperity but about intimacy with God, the most abundant life on offer.)
John did not neglect the reality that a major question on the mind of all people (in particular, his Jewish audience) was the hope of eternal life upon death. Jesus most frequently talks about eternal life both on this earth and in the age to come in John. For example, Jesus talks about how he is the "resurrection and the life," relating respectively to eternal life upon death and that which one gains in this age.
Given postmodern teens' fixation with instant gratification, I believe the Gospel of John constitutes an absolute priority text for those ministering to students of this generation. The hope of eternal life when you die has little resonance with students who think they will never die (and modern medicine suggests that there's a touch of accuracy to their mentality) and who can access nearly any pleasure through the power of the internet. John's Gospel speaks about the benefits one can experience here and now through relationship with Jesus and provides a message relevant to our young postmodern audience.