Ha! this question is impossible. I would have to say all the ATP weekends I have been to are the best times of my entire life. They were the ones curated by Animal Collective, Jeff Mangum and Deerhunter.
and I would say the worst gig I have ever been to would be The Knife in London. As much as I love the band, the crown were such a bunch of assholes it made the gig impossible to enjoy