Listing a favorite is hard, I'll list a few of the best that come to mind. There are many more I just don't remember off the top of my head.

Pearl Jam, Day On The Hill (FREE!!), Lawrence, ~1991
Paul McCartney, Arrowhead, ~ 1993Danzig, Bottleneck, Lawrence, ~1987
U2 - Joshua Tree Tour, Kemper Arena, 1987Red Hot Chili Peppers, Bottleneck, Lawrence, ~1990
Janes Addiction, Bottleneck, Lawrence, ~1990
Metallica, And Justice For All Tour, Sandstone, 1994
Sade, Sandstone, ~1992
GWAR, The Outhouse, Lawrence, ~1989
Garth Brooks, The Octogon of Doom, ~1996
Tie: Big Head Todd & Dave Matthews Band, The Octogon of Doom, ~1993, Dave Matthews, Verizon KC, 2007
Jackopierce, ku Student Union ballroom, ~1997
John Mayer, KC's City Market, 2002
A Tribe Called Quest & De La Soul, ku Student Union ballroom, ~1994