Mine? This one: "Shine On, Harvest Moon," from the powerhouse New Orleans concert.
http://www.youtube.com/watch?v=JJXS4MnkA-U I first saw her sing this song in 1968 or so, on a Johnny Carson Show. I was only 12 at the time, but already obsessed with Judy and Liza. I stayed up with a cassette recorder (remember those?) glued to the television set in my bedroom, poised to press "Record" as soon as she started singing. I had that cassette tape all through high school and college, until the tape snapped and I must have thrown it out.
But two years after that, in 1970, when I was 14, my parents took my sister and me to the Concord Hotel in the Catskills. Liza was the Saturday-night entertainment, and this was my second favorite song that night.