Oh, it depends on the phase of the year for me. During semesters, I am an early morning gardener and crafter, but I quest weekend evenings with my west coast friends. During breaks, I play every opportunity I get, regardless of the time of day (not early morning since I sleep late during breaks).
Mostly, my gameplay schedule is dictated by the ebb and flow of my kids' needs and my adult obligations in the real world.
I guess all of you would consider me a late night wizard, since I'm always on in the middle of the night, if I don't work that day. But since I work midnights this is really "middle of day" to me. Otherwise I play before bed, so mid-morning to those of you on normal schedules.
Early Morning. I wake up earlier then my parents, so I have a few hours to play before my mom has to check her email, play some games, look at the new and weather, and so on. In the mornings I can just grab something for breakfast, sit down, and play without any disturbances.
I work a rotating shift, so I am on at all different times of the day and night depending on what shift i am working. I do prefer after midnight to early early morning. The spiral always seems so much more peaceful during those times.