I assume that Founding Fathers means five people: Franklin, Washington, Adams, Jefferson, and Madison. They all had weaknesses, but I find it hard to say that any of them is overrated in public recognition, unless it be in the silly judicial quest for their “original intent.”
The most I can say is that John Adams often overrated himself. His vanity was so palpable as to be embarrassing, his jealousy of Franklin and Washington almost laughable. As Franklin’s colleague in negotiations for French aid in the Revolution he was more ‘t, of a nuisance than a help, and Franklin’s , later dictum was not far off: “I am persuaded that he means well for his Country, is always an honest Man, often a wise one, but sometimes, and in some things, absolutely out of his senses.” Adams prided himself on his analysis of government, but it consisted in prescribing a bicameral legislature and a strong Executive as the solution to every governmental problem. In his own tenure as President he was notably weak, except in his final decision to stop his cabinet’s moves toward war with France. On the other hand, Adams’s role in the Continental Congress was crucial in bringing about American independence, and in the peace negotiations with England he was much more effective than he had been in the earlier negotiations with France. If he overrated himself, it was perhaps because he had never had quite the recognition he deserved.
Although none of the others is generally underrated, I would say that Franklin is highly rated for the wrong reasons and therefore underrated for his real achievements. He is remembered for the lightning rod and for his avuncular advice to everybody about frugality and industry. ’ The lightning rod was an important invention, but it was less significant than his theoretical contributions, which laid the foundation for subsequent understanding of electricity. For example, he was the first to identify positive and negative current. Americans have never granted him the intellectual recognition that Europeans of his time did, a difference symbolized by the fact that news of his death was officially marked in France, but not in the United States, as a day of mourning.
Franklin’s advice about frugality and industry was not what he would have wished to be remembered for. He did not follow it himself in retiring from business at the age of forty-two. As a Founding Father he is recognized as the principal negotiator of the treaty with France that made American independence possible. But he is not recognized for the long years he spent before that in England, stating the position of the American colonies within the empire, until it became apparent that independence was the only way to secure American rights. Although he had little to say at the convention that formed the United States Constitution, he had had much to do with formulating Americans’ perception of what rights the Constitution ought to protect.