Eisenhower was nice.
He was both unassailable and prior to the widespread adoption of Television. Most of America did not see a litany of talking heads running him down. Also that was a different era. More moral and honest.
Reagan, too.
Reagan was a genius and a master communicator. He was a rare bird that could beat the media at it's own game. I doubt we shall see his like again.
The two Bushes as well.
Bush Senior was certainly nice to the enemy. In fact, he handed them the election on a silver platter, and thereby set back the United States as well as the world.
He only won his first election because he was perceived as a continuation of Ronald Reagan's policies.
The only GOP President that wasn't nice was Nixon.
He was nice in his first Presidential election. He lost.