Well why? Why vote for a criminal warmongerer over an anti-imperialist liberal hero?
I tried to do the list mostly without hindsight. If forced to pick between one of the two, I'd have voted for Nixon, if not, I'd just not vote at all. McGovern's campaign was perhaps one of the worst Presidential campaigns that I can recall, and though I'm generally against war, I'm also skeptical of candidates that base their entire campaign off the idea.
Plus, sans Watergate, Nixon was hardly a bad president. He supported the Equal Rights Amendment, completely eradicated the remnants of the Gold Standard, improved women's rights, wholeheartedly supported completely ending desegregation and introducing affirmative action programs, supported temporary wage and price control programs, eased tension with the Soviet Union and China, and even though he didn't get around to it until his second term, he ended conscription and the Vietnam War though he initially escalated it.
I think McGovern is great and support alot of what he wanted, but Nixon was very good at implementing what he wanted to do and had a far grander vision than just "end the war end the war end the war."