Jehoshaphat 

Jehoshaphat begins his reign by fortifying the border cities with Israel to increase security—all the while looking to God. And God blesses him immensely for zealously seeking and obeying Him. The king institutes major reforms in this vein. Perhaps his most remarkable action is to send out teachers to instruct the nation in God's laws!

Notice that there is an apparent contradiction between 2 Chronicles 17:6 and 2 Chronicles 20:33—the first stating that he removed the high places and the latter saying they were not removed. Jamieson, Fausset & Brown's Commentary gives this explanation in its note on the latter verse: "Those [high places] on which idolatry was practiced were entirely destroyed, but those where the people, notwithstanding the erection of the temple, continued to worship the true God, prudence required to be slowly and gradually abolished, in deference to popular prejudice." Of course, often what seems "prudent" to men is in fact compromise with God's express instructions. The Lord no doubt expected a stronger stand to be taken—which is why the failure to remove the high places receives repeated mention throughout the reigns of Judah's righteous rulers.

And this is not Jehoshaphat's only weakness. As the years go by he establishes an alliance with Ahab, which proves to be a mistake on several fronts, as we shall see. Nevertheless, he continues to maintain a right relationship with God overall and proves to be one of Judah's better kings.