To sum it up from the start, it's either "your thing" or it isn't. For some, working out in the morning is imperative to jumpstart their activity for the day. For others, they prefer to exercise later in the day when they're more alert & can concentrate on the activity in hand. Although I believe exercising any time of the day is most important, there's reasons to training earlier in the day proves the most beneficial to you & your goals.
For those looking to lose weight, studies have shown burning calories earlier in the day will likely spike the metabolism, which will in result burn more calories hours after the session, even while sitting. Keep in mind it's ideal to go to bed at a decent time, in addition to eating a well balanced meal the evening before. Food that is rich in lean protein, complex & fibrous carbohydrates, and unsaturated fats is recommended the evening before to provide the body with the essential fuel sources to sustain the next mornings acivities.
For those looking to build muscle, males in particular, studies have shown that an individual's natural testosterone is at its highest peak first thing in the morning. Knowing that it's an essential component to building muscle, just like those who are trimming down, it is ideal to get a good nights rest to make sure your energy levels are at its maximum capacity in order to recover faster & efficiently after the morning workout session.
In addition to all of this, your energy levels are likely to remain high for the majority of the day if you train in the morning. All of your major corporation CEOs and leaders (and even celebrities) will attest that starting their routines with a workout first thing in the morning gaurantees their best performance. Try out a morning workout from time to time, and see how it works FOR YOU. If the schedule limits your time, then try it sometime in the weekend. You'll feel and notice the difference in time.