It changes all the time. Based on sound quality, era preference, etc. These are my mainstays:
6/21/77
9/29/71
4/27/69
3/7/70
9/14/71
8/31/71
5/24or25/75
7/24/79
Any of the March '73 shows
6/27/77
I know I'm forgetting some stuff, just sitting here on the couch, watching a race, but that's what has come to my head.
Oh yeah, 6/2/73, 2/12/75, 3/19/75....