1986, all day—every day. That team was just loaded—as proven by how good the 1987 was, winning it all with "less" and beating some highly-ranked teams along the way.
That 1987 Fiesta Bowl loss will go down as the worst in Miami history because of just how good that 1986 team was.
The 2000 team not getting a crack at that national title, after beating Florida State head-to-head was another tragedy for this program.
1992 and 2002 were similar, in my opinion—not the way both lost their title games, but how both were defending champs that took big time hits on the offensive lines, which ultimately crippled both teams at the end.
Yes, Ohio State won on a bogus call—but the Buckeyes pushed around Miami's 2002 offensive line all night the same way Alabama did the 1992 Hurricanes.