I find it difficult to choose here between my top 3, so in order of their term:
Eisenhower got many things right, a few wrong. He supported the Warren court. He supported civil rights and the overturning of Brown vs Board. He supported the Coup against Mossadegh in Iran, which has led to 73 years (so far) of bad relations with Iran.
Kennedy. He was successful mainly because he was Martyred and his successor, LBJ, was masterful at exploiting it. The worst thing he actually did was Bay of Pigs. The best was the Cuban Missile Crisis, the space program, and advocacy of what would eventually be the Civil Rights Act.
Obama. The best president that managed to serve full term. PPACA was his best thing. He served in the face of the most hostile congress since the civil war.
Biden was a better president in most respects than Obama, but he had one monumental failure that destroys him: He held on too long and left the field open to Trump.
Carter could have been a great president but for three things:
1: he had the bad luck of running against Reagan, who lied and cheated to make him seem bad
2: He had some foibles on the Iran Hostage crisis. Mostly not his fault, but he gambled more than he should have
3: His relations with congress were not the best.
4: (totally not his fault) The holdover from Nixon's OPEC policy and the Iran crisis led to high inflation. His Federal Reserve Chair (Volcker) cured the problem, but too late for it to do Carter any political good
Clinton: a pretty good president, but he did a lot of stupid stuff that left him open to the Gingrich congress. Lewinsky and Iraq were /totally/ the doings of the Rs.
LBJ was actually quite a good president, if you get down to it. Unfortunately, Goldwater's tactic wound up destroying him in the end. Johnson understood that expanding VietNam was a huge mistake and that the Gulf of Tonkin incident was nothing, but Goldwater managed to inflate it to something that Johnson could not pretend to ignore. The Great Society, Voting Rights Act, Medicare, etc., were really good things. He would be at the top of this list without VietNam.
Ford: The least bad GOP president. He had the luck to serve in Nixon's wake and looked wonderful by comparison. He did very little, and was convincingly (and rightly) defeated by Carter.
Bush41: Perhaps the most competent R since Nixon, but mostly a promoter of Evil. His alignment with the Oil industry being his worst problem. Clinton mopped the floor with him in '92. GOP'ers will tell you that Clinton only won because Perot stole votes from Clinton, but the numbers tell a quite different story.
Nixon. Corrupt but somewhat competent. Screwed up LBJ's peace settlement with VietNam to undermine him (and his successor Humphrey) in the '68 election. Understood environmental issues better than many of his successors. Watergate.
Bush43: Incompetent and Corrupt. Knew he was out of his depth, so he hired crooked people to do most of his thinking for him. Reacted exactly wrong when the CIA told him that Bin Laden was determined to attack again. September 11 was his least terrible failing. Invading Afghanistan was a huge mistake. Invading Iraq before he'd finished with Afghanistan was a disaster.
Reagan. Trump would have been impossible without Reagan's opening us to corruption. Reagan was incompetent, corrupt, did lots of stupid stuff (e.g.: he sent soldiers to Beirut, despite repeated warnings. A truck bomb killed hundreds of them. So one week later, he invaded Grenada.) Iran Contra. There are lots and lots of these. He had enormous personal charisma, which for those of us with functioning BS meters, is a disqualifier.
Trump. Incompetent, Immensely Corrupt, Stupid, remained in power by threatening people. Before Trump, it was a contest between Reagan, Buchanan and Harding who was our very worst president. Trump takes the prize in a landslide. He may have destroyed the United States. It's remotely possible he will destroy life on earth.
