I'm sure there are some worse people at the state legislator level, since it's a big country, and a broad spectrum of awfulness exists. But among reasonably prominent American politicians who I'm aware of, I can't think of anyone who I think would be a worse choice for president. There are certainly people who are worse along certain dimensions. E.g., Trump has at least run a large organization before (if not very well) so I'd guess that Ben Carson would be even more incompetent than Trump in terms of management abilities. But Trump is pretty much uniquely terrible along a combination of dimensions:
1) He is horribly insecure, way more narcissistic than even your average politician, and has the maturity and emotional intelligence of a grade schooler.
2) He has billions of dollars of assets around the world, with no real transparency behind any of it, and so his administration is corrupt on a scale that would be impossible for most politicians.
3) He has a mercantilist view of international economics that, among other things, pushes him towards burning up the US’s relationship with many of our traditional allies because “they’re ripping us off on trade” or whatever.
4) Relatedly, he doesn’t attempt to justify the US government’s actions, either at home or abroad, in moral terms at all. As Jonathan Chait
notes here, Trump has praised authoritarian leaders for their ruthlessness countless times over the years, including praising the Chinese government for their reaction to Tiananmen Square:
Peter Beinart is also worth a read on this topic:
”For Trump, “We Have a Lot of Killers" Isn’t a Criticism”I mean, who else says “Let’s steal other countries’ oil.” or “Let’s kill terrorists’ family members on purpose.” It’s pretty horrific.