I used to debate which is better for me right from school days when an exam was coming up. I used to mostly stay up late rather than wake early (unless I had to do both!). The main reason for this was staying up at night was a safer option. Let's say you had some stuff to complete. You estimated it would take two hours to complete. So, you decided to do it in the morning and woke at 5 a.m. because you had to start getting ready at 7 a.m. Now if it got extended for whatever reason, panic would set in and possibly you may not finish what you set out to do at all! On the other hand, if you stayed up late, you had the entire night ahead even if things took longer than you thought they would.
The morning larks however would argue that you would generally finish whatever would otherwise take 2 hours, in an hour. Simply because your mind is totally fresh, completely rested and very efficient. This argument has merits. I have switched to a consultant model with the software company I worked with. So, I work from home, work according to my convenience and bill for the hours put in and the work done. I find that I am at my best in the morning. I am usually done with my dialysis around 5 a.m. and then have about an hour to two hours to finish off some work (unless I feel like and am able to go back to sleep). I am able to complete really complicated stuff very quickly.
The Hindu scriptures extol the virtues of the morning too. Most scholars arise early in the morning and practice their shlokas at that time. I guess, for work that involves the mind, no time is as good as the morning. Especially when there is no deadline involved.
... http://www.kamaldshah.com/2011/04/morning-lark-or-night-owl.html