I love both, but I have to go with night. I am naturally a late night person, in fact I am having a hard time getting to a morning person's schedule. I love the quiet of the night, as well as the stars and the moon.
Mmmm, this has gotten me to think about my sleep schedule, which is ridiculous, to be frank. I don't mind getting up in the mornings, and heck, I don't mind getting up as early as 4, 5, or even 6 AM. And I have no issues staying up as late as possibly 3 AM. Though preference-wise I'd go for mornings, since I'd have a lot more time to do things during the morning than I would at night.