All I know is that I remember reading Trey stating that he considered Phish retirement after Clifford Ball. That should speak to the quality of the shows that were played. 8/16 and 8/17 were considered two of the top 25 greatest shows ever played by the Pharmer's Almanac that came out after 2000. I wasn't fortunate enough to be able to attend any festival besides Coventry, so I can only speak from the recordings of the other shows, but if I had a time warp and, excluding Cypress, had to choose one festival to go to, I'd choose the Ball. And that's coming from someone who cherishes improv just as much as the next fan.