It may be considered heresy to post this on freerepublic but I’ll say it anyway: Barry Goldwater.
Underrated in 1964 perhaps but highly overrated from the post-Reagan period onwards. The news that he helped his own daughter abort his own grandchild does not sound very conservative to me.
I supported Goldwater then saw him appear on a Norman Lear program for “People For The American Way”.
It was a radical leftist organization and there was Goldwater appearing on it to support those jackasses. He was conservative on financial matters but very liberal on social issues.