Truman. While I consider Eisenhower to be a good President on balance, his stock as President as really fallen for me in recent years. Truman IMHO was also dealt a much tougher hand than Eisenhower was and Truman, despite having more to lose politically, pushed for Civil Rights a hell of a lot harder than Eisenhower did. Ike was also the first President to actively pander to the religious right.
This is a very good point I forgot to consider. God's Own Party (which I read about two years ago) fleshes out Billy Graham's strong support for Eisenhower and how he was the first president actively supported by the religious right (other than Hoover, but Hoover didn't court them - it was mainly out of anti-Catholic bigotry).
A lot of the GOP’s ties with the religious right under Eisenhower and even Reagan had a lot to do with the Cold War . Much of the Cold War narrative was that it was the Religious Capitalist West vs the Atheistic Communist East