Evening workouts are my favorite but since trying morning workouts, I like those also.
I have noticed that I must go about each workout differently. If I do it in the morning I have to do different excercises than in the evening.
Morning consists of more stretching and less strength or really 'pushing it'. More warming up. Actually, I like yoga or something like that. In the evening, I am stronger, more flexible, and can 'push it' more as I am already awake and probably have some stress from the day. I also do some stretching after the workout in the evening to calm down.