To answer my own question, lol, I would say 1984, if only because Mondale was more electable than McGovern and due to the fact that unemployment was higher in 1984 than it was in 1972. I'd also say 1984 because Nixon in 1972 (and correct me if I'm wrong) seemed more palatable to Democrats than Reagan did.
Nixon was expecting a very tough re-election fight in 1972. At the start of the year, he was running even or slightly behind Edmund Muskie in the polls. And there was a reasonable chance that George Wallace would run again as a 3rd party candidate.
In his memoirs, Nixon never expected McGovern to get the nomination. With a split Democratic Party, Nixon thought that at the DNC, the nomination would go to Ted Kennedy as a compromise candidate.
These, and his foreign policy achievements, turned what looked to be another 1968 (at least in Nixon's mind) into a complete rout in 1972.
Reagan was pretty vulnerable between fall of 81 and late 83 early 84 though to. Reagan also had greater backlash in 1982 than Nixon did in 1970.
1982 wasn’t really that bad for the GOP , they still were in better position after 1982 than they were before 1980 .
Usually in midterms all your gains from the previous cycle are wiped out , which was not the case in 1982