1. Reagan
2. Obama
3. Bush Sr.
4. Clinton
5. Biden (so far)
6. Bush Jr.
7. Trump
Reagan ended the Soviet Block and freed the East Germans (among others). I get that there was a hell of a lot else going on that lead to all of that, and I get that Reagan was a senile old man with some odd political philosophy, but I'm not at all convinced that the cold war fizzles out nearly so effectively and non-violently without Reagan's presidency.
Obama was just a smooth character all around, and he took over a shit show and made it work again, well enough to continue functioning fairly effectively after he was gone in the midst of a total clown show. He also got Bin Laden (this was likely a "right place, right time" thing) and moved the healthcare stalemate forward (which, in my mind, was a "right person for the job" thing). Admittedly, Obamacare is messy, but it's something and given the political environment there's been a whole lot of nothing from everyone else.
Bush Sr was nothing special, because he never got that second term. But there's little question that he got voted out prematurely because of Ross Perot, and it feels like he might have done better if given more time.
Clinton is a bad person, and while he had some political victories and policy successes, he also helped set the table for 9/11 and, yes, the 2007 financial collapse. The only reason he gets to be this high is because everyone below him is such a bad president.
Biden is Gawd awful... so far. Took over a clown show, and made everything worse... so far. Everything. Covid. Partisanship. The border crises. Everything. So far. And that's the only reason he gets ranked above Bush Jr and Trump. Because he still has some time.
Bush Jr I actually like better than this. He did some good things with the Latin community, put some good pandemic policy in place (that was later undone by Obama and Trump, unfortunately) and seemed to genuinly want to work across the isle. Speaking of which... Iraq. 'Nuff said.
Don't even with Trump. Policy-wise? Not nearly as bad as people make him out to be. Some good policy on education and opportunity for black people. A wall on a border doesn't seem like anything weird or particularly racist to me. And otherwise pretty standard conservative leaning governance. But the president is everyone's president. A huge part of his job is to set a tone. The tone he set was Monday Night Rawesque. Which, until Covid and BLM, I would have argued was off-putting but not enough to put him below Bush Jr and Iraq... but people died. A lot of them. People are still dying because not getting vaccinated or masking or social distancing has become a political stance aligning you with Trump. And say what you will about BLM burning businesses to the ground (which they did, and which I've said plenty about), the Confederate Flag marching through the Capital Building is a disgusting look, and him cheering it all on from the White House (which he absolutely did), is enough in itself to put him firmly at the bottom of this list.