It really doesn't matter. Calories burned are calories burned. You don't want to do it after eating though, so that's one stipulation. That's the "short" answer.
I like to go during my lunch hour from work. It keeps me from going out to eat saving me money too. It tends to make me not as hungry afterwards also. Sometimes working out 1st thing in the morning is good b/c it gets you going for the day, plus it gets it out of the way. It also avoids the issue of getting squeezed out if the day gets busy as it goes on. If you like doing it at night, go for it.

Morning is the best time to exercise..The majority of people who exercise early in the day, It is very easier form of exercise habit.