The kings who are most written about in the books of Kings are the kings who either kept the covenant well, broke it very badly, or had an important encounter with one of God's prophets. Ahab son of Omri and Manasseh broke the covenant so that it was dangerous to Israel, so the author wrote a lot about them both; Hezekiah (2 Kings 18:1-20:21) and Josiah (2 Kings 22:1 - 23:29) are written a lot about because they tried to remind the people of their covenant promises. They are the only two kings who the writer is really happy with for their loyalty to the Lord.