For Wild Nights, Hot and Crazy Days it will forever be this one: New Year's kiss, 1:00 AM on 01 January 2000 (the kiss came an hour late because Troy had been stuck at work, so instead of kissing at midnight Atlantic time we waited until midnight Eastern time). This was the kiss that sealed the deal. We declared our love for each other that evening.
A close second would be this one, which shows when we got married in 2017:
For Finding Daecon's Way/Defining Daecon it's probably their own honeymoon kiss: