Out of them all, I think I like 3pm the most, as it reminds me of when I first started playing the game. I actually do remember sitting in the living room on Christmas day at around 3pm, running around my town and fishing.
I cannot decide between 1 AM and 7 PM, both for different reasons. 1 AM is so peaceful and calming... but 7 PM is just what comes to mind when thinking about animal crossing. I really adore both though and feel they are too different for me to decide between. I love the music in this game a lot, it has so many good memories with it for a lot of us. That first summer we all played, I am sure we all had that one or two songs that brings us back to that time.
Definitely 4AM. It sounds really calming, especially during those stressful or busy nights. I have the soundtrack on my phone and would listen to 4AM whenever I needed to shovel the driveway in the winter before going to sleep for the night.