I am going to name the five worst presidents of all time, from a libertarian perspective. Of course, this is highly subjective and you can use different criteria. I am going to name the worst for liberty at the time they were president and also the lasting effect they had against liberty.
While many people will name the current or last president as the worst (Republicans will name Obama and Democrats will name Bush), they really aren't in the top five (although Obama still has time to make it there) when you consider some of the disasters of the past. Obama and Bush certainly deserve a spot in the top 20 worst of all time, but not the top five.
I would like to do a list of the top five sometime, but it would actually be the five who were the least bad. The list would be unlikely to include anyone from the 20th century and certainly not from the 21st century. The top five would probably all come from the 19th century.
So here is my list of the worst five:
1) Abraham Lincoln - While Lincoln is revered by so many, he did great damage to the country. He supposedly ended slavery, but that was just an effect of his war. Slavery would have come to an end anyway, and it could have been done peacefully. Lincoln waged a massive war, which killed over half a million people. That is when the country was much smaller. It was easily the deadliest war in American history, at least for Americans. It severely diminished states' rights and centralized the national government. His policies definitely had a lasting effect that we are still paying for today. He was really a brutal dictator in many ways. He killed and imprisoned those who disagreed with him. I am glad to say that it is highly unlikely that any president today could get away with the things that Lincoln did to his fellow Americans.
2) Woodrow Wilson - He presided over the Federal Reserve Act, the 16th Amendment, and the 17th Amendment. These three things all happened in his first year of office. In 1913, we got the Federal Reserve, the federal income tax, and the direct election of senators (another killer of states' rights). This alone would have been enough to put him in the top five. On top of it, he put America into World War I and instituted a draft, much like Lincoln. With American entry into World War I, it set the stage for the spread of fascism, World War II, and eventually the cold war. Wilson was awful on all accounts, foreign and domestic.
3) Franklin Roosevelt - Roosevelt was horrible on economics. He instituted his "New Deal", which gave us Social Security. He continued the Great Depression by not allowing the free market to work. He really began the massive welfare state in America. While Roosevelt is looked on highly by many for his leadership in World War II, I beg to differ. He provoked the Japanese into attacking America by imposing oil embargoes and other restrictions. There is even a good chance that he knew the attack was going to happen at Pearl Harbor and did not warn anyone. This really makes him a mass murderer. He may as well be since he loved his "Uncle Joe" Stalin so much. As a libertarian, there is one positive thing that Roosevelt did during his reign in office. He ended alcohol prohibition. This was a great thing for liberty and the violent crime went way down, even in the midst of the depression.
4) Lyndon Johnson - It would not surprise me if Johnson had a hand in the assassination of JFK. It turns out that Jackie thought that. Johnson, of course, was a war president. He is responsible for the deaths of millions of Vietnamese, along with many others. While America was already involved in Vietnam when Johnson became president, he is the one who lied Americans into war and really started the violence. On the domestic front, Johnson gave us his "Great Society" that was anything but great. He started up Medicare and Medicaid and began his "war on poverty". He was really a disaster in every way.
5) Harry Truman - Truman belongs on this list because he used two atomic bombs, killing hundreds of thousands of innocent Japanese civilians. It was not necessary to end the war. The Japanese were already willing to surrender. For this alone, Truman belongs on this list. He also presided over most of the Korean War. On economic issues, Truman was also bad. The one good thing that he did was that he didn't do anything at the end of the world war. Due to his lack of action, the economy was finally able to recover for the first time since the 1920's.
There are certainly a whole bunch of other presidents who were horrendous. You can go back to Washington (the Whiskey Rebellion) and Adams (the Alien and Sedition Acts). You can include the other Roosevelt. You can include Obama and the younger Bush. But really, almost every president of the last hundred years was a total disaster. It's just that some were worse than others. For the top five worst though, they definitely all need to be war presidents.
It is no coincidence that all of these war presidents were also horrible on economic issues. The two things are related. A statist politician believes in big government in all arenas. What is scary though is that most historians regard many on my worst five as the best.