I could say my first solo, but I wasn't too happy with it; my second solo was pretty good. I flew with air cadets at school, so I've had a few dusty memories of aerobatics in a Chipmunk, watching Tornados refueling out of the side windows of a VC10, etc. They were all good. The <3000ft tour of S England in a C130 with <500ft parachute drops was cool too.
However - as non P1, my most memorable experience was recent, with an outfit in Cape Town who fly an old Huey. I was strapped in the R Gunners' seat, no doors, mid-summer, and they then spent the next 30-45 minutes skimming down the beach and coast down to wavetop height and what seemed >100kt, pulling sharp turns and climbs, diving over hilltops, and so on. I'll have to compile all the video I shot of that and post it one day.