Can't do better than a four-run homer that wipes out a 4-run deficit. But to me, hitting HRs that finally beat the Yankees will always be the most impactful. Other underrated Ortiz longballs: the 8th inning shot off Gordon that started the Gm 5 comeback in '04 (before his extra-frame walk-off single)...
... and the one everyone forgets -- a solo in the 8th of Gm 7 '03 ALCS off Wells, who was brought in just to pitch to Papi. That round-tripper made it 5-2, Boston -- more than enough for Embree, Timlin and Williamson to close it out.