Eisenhower, Reagan and Clinton had the most public support of the listed options. You can say they defined their decades.
Nixon and Bush were very polarizing. Large swathes of the public hated them from the beginning to the end.
Nixon had quite decent approval ratings (in the 60% range) until Watergate started unfolding.
His 1968 margin of victory wasn't that great compared ti Eisenhower/Reagan/Clinton's landslide wins.
True, but there's a middle ground here. He wasn't overwhelming popular like those three were, but he
was reasonably popular with the general populace until 1973. Also, his '68 margin was respectable (in a complex three-way race), and while it wasn't as large as those of Eisenhower/Reagan/Clinton, neither was it a squeaker like Carter's or both of Bush 43's.
And of course, his '72 margin was rather impressive.
If large swathes of the population had hated him at that time, that margin wouldn't happened, despite McGovern's weakness as a candidate.