My list, in no particular order:
1. Nixon - Everyone knows why Nixon was a shitty president.
2. Hoover - He was a great man and a great American, who stood for everything the "balanced budget" conservatives claim to stand for but aren't willing to follow through on (cutting government waste, paying for spending with taxes to balance the budget, etc.). His policies were a horrible failure, though, and while it's unfair to say that he created the great depression, his policies made it about 100x worse than it had to be.
3. Harding - Appointed the Ohio Gang to his cabinet and oversaw the most crooked administration the United States has ever had.
4. Carter - Like Hoover, he is a great American and a great human being, but a horrible president. The Iranian Hostage Crisis was just the cherry on top of his 4 year tenure.
5. Coolidge - A firm believer in laissez-faire government, who didn't really do anything of note while in office, and did absolutely nothing to even try to slow the great depression, which came about right as he was leaving office.