I give Truman high marks for his support for civil rights, the Fair Deal (good proposals, though few passed) and for NATO, the Marshall Plan, etc. Communists rivaled Nazis as mass killers, so containing Communism was a moral and existential imperative. Nuclear energy should be part of our greenhouse reduction strategy.
Eisenhower helped save the GOP from isolationism & McCarthyism, and moved the party toward moderation in accepting the New Deal legacy. He put two brilliant justices (Earl Warren and William Brennan) on the Supreme Court (though Eisenhower called them his two biggest mistakes). Out of respect for the Constitution, he enforced the Brown decision even though he disagreed with it. On the other hand, he called his Mexican deportation program Operation Wetback, and his American Indian policy “termination.” CIA shenanigans peaked on his watch.