Depends a bit on whether you're naturally an early riser or night owl. If the latter, then later flight out, IMO, no question. 2-3 hours sleep on the flight and it's no different to having an early evening snooze and then staying out til 4 or 5 am.

Coming back, I don't think either of the flight times are ideal, but I'd go for the latter. My ideal is to get as close to 8 hours sleep on the plane as I can. Then I can get through the day and go to bed at normal time. Landing too early, I find, means 8 hours sleep or no, you get the late afternoon fatigue big time, and it's difficult to fend off.