Jimmy Carter was the only US president in my lifetime who I am comfortable saying was a good human being.
I'm not sure how good a president he was, although a lot better than he was made to look through deliberate sabotage of his presidency by the Republicans, but AFAIK he seems to have genuinely been a good person all the way through.
I believe he is the only President in recent years under whom the US didn't invade or participate in a war against another country.
Edit: fixed typo