That's a really tough question, I need to make the choice between "best" show and most fun show.
I'd have to say the best show was John Luc Ponte outdoors night time concert in a driving storm. It was miserable for us in the stands, but there he was out on the point of the triangular shaped stage playing like a madman with the wind blowing in his face, long hair straight out behind him. It was a great show.
Most fun would have to be the Stones, Tatto You Tour, general admission, 1981, JFK Stadium in Philly.
The 6 of us, myself, my girlfriend, another girl and two guys, got there at about 5:00 the night before and partied straight through the night until it was time to line up at the admission gates at dawn. I think the only person to get any sleep at all was my girlfriend who crashed for about an hour in the back of the car.
One of my favorite memories was from before the show even started. it was no more then 7:30 in the morning and the PA system was blasting Roadhouse Blues by the Doors. Now this was back in the day when you could bring a cooler into the show with you so we had dragged 3 big coolers stuffed with beer and ice to no more then 50' from the stage. The speakers blared, "Woke up this morning and I got myself a beer!" and the entire place went nuts
The show opened with the Hooters, a local band who had just put out their first (and only?) successful record, followed by George Thorogood and the Destroyers and then Journey. We thought they were all great. Journey had just put out that big album of theirs and no one was sick to death of em yet.
I'm not even sure what time it was when the Stones finally came on stage. The entire crowd went wild and pushed forward. Up front we were packed so tight that at times I'd be swept in any direction with my feet not even touching the ground! To this day I still can't believe no one was killed.
Fortunately the girls and one of the guys had left to find a bathroom right before the Stones came on and weren't able to make it all the way back to the front. I don't think I could have stayed right up where I was if my girlfriend had been there. She was just a little thing and couldn't have handled the crushing preassure of the crowd, I woulda had to get her out. As it was, quite a few girls and a few guys who couldn't take it were being handed along over the top of the crowd for medical attention.
After the show we all met back at the car, partied and unwound until the lots cleared out. I'll never forget the sight of the parking lot when it was all over. I've gone to dozens of shows, 100's of NFL games, and I've never, ever seen a parking lot trashed even close to as bad as this one was. The driving lanes out looked like trails in the woods, just two tire tracks though the garbage.
I know I couldn't survive any of it now, the crowd, the nonstop partying, the massive sleep deprivation combined with the insanity, but man it was fun then.