George Bush or Hoover. Bush because...c'mon. Hoover because he knew what steps he could and should have taken to fix the economy and end the depression, but wasn't willing to do them because of his ideology. That is the worst thing a leader can do, to put ideology above reality.
I would disagree Jimmy Carter was one of the worst Presidents that this country has had the misfortune to see. He gave us 20% inflation and his foreign policy was a series of disasters which lead to the fall of the Shah and the establishment of a government that has been hostile to the United States ever since. Terrorism would not be the thrat it is today without his stupid decisions. No Iran-Iraq War , no Gulf War,no soviet invasion of Afghanistan and no Taliban.
Carter didn't create the stagflation. Events preceding him in the 1970's and in the world around him created that. He just couldn't deal with it all in one term. However, he appointed Paul Volcker Chairmen of the FED, whose policies of economic recovery were carried out under Carter and in Reagan's first term, and those were what caused the economic boom of the 1980's. So Carter term 2 would have seen the same economic recovery of Reagan term 1.
And Carter didn't cause the overthrow of the Shah. Angry Iranians kept under the thumb of a foreign funded tyranny did that. You may blame Carter for the handling of the hostage crisis (which Reagan didn't do anything about either), but you cannot blame Carter for the explosion of tensions in the Middle East. The causes are too large and too old for that. And he did manage to bring together Egypt and Israel which I think few other Presidents could have done. And the Carter administration, unlike Reagan, did not funnel Iraq and Iran arms which can be attributed more to the tensions in the Middle East and the fault of a President than Carter's not wanting dead hostages or Vietnam 2.
But by far the worst Pres since 1900 is Barack Obama.
In so many words to save me breath, and supposing everyone already knows what the disagreements over the above statement would be, this is totally biased and baseless speculation.