Certainly a race to the bottom here, it's hard to pick. I'm leaning towards Reagan for a variety of reasons in that he basically solidified America as a heavily capitalist, bootstrap libertarian culture at a time when a stronger government and social safety net could have pushed us in a different direction. Reagan's influence is still being felt across both parties and the American electorate. He is responsible for countless abhorrent crimes, from the AIDS crisis to the War on Drugs to Iran-Contra and so on.
Unlike Trump, who is an obvious dumpster fire and vile creature, Reagan did a good job of disguising his nature to white moderate middle-class America, and that's why he was more dangerous. But hey, Donald, it's still early days, you can make a comeback!
Another strong contender is obviously Bush 43 and the massive loss of life caused by his illegal wars.
