The defeat at Macc in 1995 was pretty annoying, especially as we'd have won the league if we'd beaten them home and away that season (and other results had been the same). But my worst moment perhaps was not actually a defeat, but when we were 2-0 down to Woking at half time in the home match this season, and things seemed so bad that I almost didn't care any more. By the same token, great credit to management and players for turning it around in the second half and the rest of the season.
I would add about the Lancaster match that it felt really really bad because we had never been relegated before the previous year, the Wigan and Tottenham matches were still fresh in the memory, and Lancaster were the smallest of small Unibond clubs beating us at home. (That reminds me, the Cheshire cup defeat at Vauxhall GM was pretty dire too, I seem to remember Jo was fuming at the end. Ecky used to joke that they would take four supporters to an away game all the way from Wooton, all coming in the same car).
Best wins are between Macc in the snow (3-2, Pritchard) and the recent 1-0 (Lawrie).