If we looked at the first book written it would be 1 Thessalonians or possibly Galatians. And if we looked to the last it would be Perhaps Revelation. So why is the New Testament arranged the way it is?
Gospels and Acts
Letters
Paul’s
Letters to Churches (Largest to Smallest)
Letters to Individuals (Largest to Smallest)
Non-Pauline (Largest to Smallest)
Revelation