Was up at 5:20 this morning, on the road till 8. My job is pretty unpredictable in terms of how late I have to stay at night, so the morning is the only time I can be sure I'll get my workout in. Even when I had a standard 9-5, though, I still preferred to work out early and keep my evenings to myself.
I prefer to ride early-ish, though not as insanely early, on the weekends for two reasons: The roads are less crowded, plus it gives me most of the afternoon to spend on errands or with friends/SO.