Two small points:
1. All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness.
2 Timothy 3:16
2. Throughout His Word, Jesus Christ spoke often of hell and the fact that unsaved, unredeemed men would face an eternity in damnation. Mankind would never write a book condeming himself to hell.
The Sermon on the Mount and the Ten Commandments are possibly the best the Bible has to offer...
Actually the entire Word of God is precious and priceless; giving guidance and answers to everything from finances to marriage to child rearing. However, the best that the Bible "has to offer" is the message of salvation; the good news that we as fallen, damned sinners do not have to spend eternity separated from God. There is a way out of the punishment that we deserve and will receive apart from our trusting Christ and accepting His sacrifice on the Cross in our stead for our sins.
Without that message, nothing else matters. Nothing.