A lot of people try to be cute and answer “William Henry Harrison, because he died before he could do anything,” but IMO the question should be limited to Presidents who have a record to scrutinize (“well that would include William Henry, because he has a record of dying in office!” – you know what I mean).
A related “cute” answer is “I don’t have a favorite and neither should you, all these guys are criminals, it’s like asking who your favorite Mafia Don is” (It’s Lucky Luciano, btw). IMO if that’s your answer you can skip this question as “not relevant to your interests.”
Anyhow I’ll answer it this way: I know there’s a sort of mini-boomlet for Coolidge now, but that shouldn’t detract. IMO he’s the last fairly good Republican President, and Cleavland is the last fairly good Democratic President (see? I can be bipartisan! Yippie!); sure they did some things that one can be critical of (no one is perfect), especially from an anarcho-libertarian standpoint (whose perspective is that no decent person should aspire to such an office in the first place), but they were basically concientious constitutionalists.
Now, as for what my “cute” answer might be, another method of selecting a “favorite President” could be to pick the most brazen reprobate available, the one who most nakedly ruled contrary to the integrity of the office, who stole everything that wasn’t nailed down and openly favored his cronies and supporters, lavishing them with bounties and used his office to blatantly crush his enemies. In other words, the one who most readily serves as an illustrative example. But here there are so many contenders that it’s hard to crown just one without feeling like slighting another for whom a good case can be made.
But if I was forced at gunpoint to choose right now from that deck full of jokers, I suppose I’d pick a man admired by “left and right” alike, Teddy Roosevelt, a man who forged new paths in all of these things and got away with it, grinning that big, shit-eating grin of his. (Counterargument: “but he didn’t build his legacy of Presidential greatness atop a pyramid of bodies, blown apart in wars started during his term, howevermuch he might have seemed like he wanted to, his reign was actually relatively peaceful.” To which all I can say is: I told you it’s a hard choice…)