Myself?
I'd give just about anything to have been a fly on the wall on the rancorous day when "One" was recorded. To be witness to a U2 shouting match, and/or uncharacterisitc icy silence, when they were the closest they had ever came to breaking up, (if you read Flanagan's book you will realize just how dire the band's situation was then) then hearing Edge coming up with that opening riff, then Bono joining in, and how the track shaped up, and was recorded within the next hour. To see all that antagonism melt away before what must have a been a divinely inspired moment. I wonder if the guys all engaged in a massive hug afterwards, and if there were even any tears?
What I wouldn't give for the security video from that Hansa studio, if it existed....
That would be my magical moment, even if the footage doesn't exist.