We get lots of questions about the difference between a mechanical watch and an automatic watch. It is really a rather simple distinction. A mechanical watch needs to be manually wound each day to keep it running where as a mechanical watch can be powered by the wearer’s movement. Basically, there is a rotor in the back of the automatic watch which spins as the wearer moves their arms and that powers the watch. That isn’t to say though that an automatic watch is better or worse than a mechanical watch it is more a matter of what you want.
An automatic watch has the most obvious advantages. You don’t have to wind it each day, so long as you wear it regularly you will be good to go. The watch is also more technologically advanced as the automatic movement was brought in to solve the winding problem. The trade-off is that the watch will be thicker, the rotor takes up room and as such you will have a less slender case.
Automatic watches are by far and large the most popular winding mechanism. It is more convenient and convenance sells. However, there are fans of mechanical movements that will argue for the older mechanisms. First and foremost is the daily habit itself, many fans of mechanical watches like the routine of winding the watch last thing at night or first thing in the morning. It becomes as much a staple of their day as having the first cup of coffee for the day or last cigarette before bed. There is a certain appeal to having a few seconds a day dedicated to winding up a watch. The other appeal is the vintage aspect, many watch models began life as manual winds and some persist as manual winds, such as the Speedmaster. So for some the authentic article must be manual wind.
It is always in the end personal preference. Do you like the convenance or the routine? Is the trade off on thickness worth the time spent keeping the watch going? It is all a matter of what you look for in a watch.