5 pm reminds me of a nice little plaza area with a park in the middle and some small boutiques surrounding it. It's very peaceful and it makes me feel at ease.
11pm and 6am. 11pm is like a very nice, calming serenade, that helps you relax, and feel ready to sleep. 6 AM has a quirky "It's the start of something new!" feel to it, and is like audible coffee, waking you up in the way you want it to. I found myself waking up at 6 in the morning, groggy, and I open my 3DS because why not, to have ACNL running, and I hear this music, and I find myself actually waking up quite nicely.
I have several and it's so hard to just chose one!
12 AM just from the Summer 2014 nostalgia, as it was the hour I returned from bug hunting at the island with friends.
5 PM as it reminds me of the fall/winter days when I play after finishing my homework.
I also love 4 AM, 6 AM, 9 AM, 7 PM, 8 PM and finally 11 PM.