It used to be a question between Woodrow Wilson and Jimmy Carter. But hands down, Biden won the title, and he did it in less than 18 months!
Obama has to be in this conversation, too.
The latest ranking by professional historians had Trump at #41 (essentially tied with Pierce and with only Andrew Johnson and Buchanan lower). That tells you all you need to know about their ability to judge without letting their own political views dictate the answer. Woodrow Wilson used to be ranked pretty high (as an activist, Progressive President) but has dropped because of his racial views.