I would say Trump, but when one thinks about it, corruption has been widespread in several administrations. You have Johnson lying about Vietnam, Nixon with watergate, Regan with Iran contra, and who knows what else Cheney and his other cronies did to try to spread their ideas of democracy. Then you have the second Bush manufacturing evidence to justify a war that cost thousands of American lives and many times that in Iraq, both enemies and "collateral damage". And of course Clinton the Lewinski escapade, which imo is less serious, at least in effect, than the other abuses of power. If I had to pick one that I think was the most ethical president, it would have to be Carter. Not saying he was an effective president, be I do believe he was above corruption. I would also say the first Bush and Obama, whether one agrees with their policies or not, really did not have administrations riddled with corruption.