On work days, 5:50AM.
On weekends (or days I don't have work), 5:30am. (Hate this)
If I was up late the night before, I'll end up waking up around 7:30am. I can't sleep past 8:00am, no matter how hard I try. I just can't stand to be in bed past that time. However, I do end up taking short naps around noon or 1pm if I didn't sleep the night before.