One or multiple watches?
If you are planning to buy a watch that you can wear anywhere, it has to be neutral stylistically speaking. This means that it will be so much easier to pair it with almost any color and wear it at all levels of formality.
If your budget allows you to own more than one watch, then the options kind of open up a bit more. You can choose a sleek option and an understated one when you want to be formal. A shiny and broad one can be a great conversation piece. If you want one watch, you have to be restrained and it should be plain. Also, note that a black leather watch does not pair well with leather shoes that are brown in color. However, you notice that there are some leather watches that can use interchangeable bands.
Leather strap or metal band?
Metal bands are neutral. The only thing you have to consider with this kind of strap is the color of your belt buckle and your cuff links. Men do not wear lots of metal and this makes a metal strap one of the best options.
As for leather, it has to be matched with your belt and shoes, especially if they are made of leather. Leather looks quite simple compared to metal. Plain black leather is perfect for formal situations. Leather gives that comfortable attitude and this makes it approachable.
Case and dial style
The visible face of a watch is what we call the dial while the case is that which encloses the movement and the dial. Normally, cases are metal or plastic made. Apart from uses in outside sports or utility, it is not reasonable to own a plastic or rubber watch, especially for a man. You need to choose the kind of case that you want and there are so many options available. The dials also come in many colors. Some are very simple and plain and it is usually deliberate. Black dial with a metal case is quite common with men. When a watch has more contrast, then it becomes even more noticeable. This means it will be less formal. Plain colors are perfect for business dress code. The shape of the dial and the case are aesthetic in nature. There are different shapes that you can choose from.
Buying a watch has a lot to do with your own taste. You should remember that not many watches will match with all outfits. So as to do this, you may need to invest in two watches. The metal bands happen to be much easier to match even though leather appears a bit dressier and natural.