Live, there have been a few, including:
Buddy Rich, twice - ‘nuff said.
Hawkwind live ‘79, Preston - first ever rock gig. Blew my head off. Amazing.
Manowar live ‘84 Manchester - first time I saw them. Went for a laugh expecting them to be terrible; they were unbelievable. Saw them a few more times but that was the best; spoke to Joey DeMaio at the next gig I went to on the tour and he agreed Manchester had been a great gig.
Bow Wow Wow live Manchester Uni on the When the Going Gets Tough tour. Loved the band but expected them to be crap live. They were awesome.
Seeing Lissie playing in a bar in Cornwall, bumping into her at the airport the next day and then travelling back on the same plane. Even now, does not compute.
There are many others, but they stand out.