I don't agree with everything Obama did (deportations, bungling explaining the ACA, drone strikes) but I don't think anyone can claim he's not a decent human being. He believed too much in the system and in the American people, and wouldn't reduce himself to the cynicism that rules the DC power plays.
Trump is fundamentally indecent. A con man, a bully, a short-fingered vulgarian, blindly narcissistic and pessimistic about the future and distrustful of anyone outside of his family. He doesn't believe in America or Americans, he only believes in his smug superiority.
FTA: «All this can obscure what I think will, in the coming years, be most missed about Obama: his decency. His scandal-free administration. The seriousness with which he approached his job. The faith he had in the American political system, and in Americans.
Hope was the basis of Obama’s politics. It’s the basis, in ways I did not truly appreciate until the end of his presidency, of Obama’s personality. His political career is built on a vision of who we could be, and the absence of that vision will be felt as he is succeeded by a man whose politics are built on a nostalgia for who we were.»