Size is important too. It’s important for the bracket to properly support the shelf that it’s holding up. A common mistake is to buy brackets that are either to big or too small for the shelves. If they’re too big then they’ll stick out, and if they’re too small then the shelf could be unstable and dangerous. The projection of the bracket (the part that sticks out from the wall and holds the shelf) should extend to within an inch of the outer edge of the shelf.
The price of wall mounts can vary widely, and even though the cost may be small in comparison to the cost of your TV, a lot of people find that even the most basic types of mount can actually be relatively expensive for that they are. If you already have a cabinet to house your receivers and other equipment, it can look slightly odd to see the TV mounted to the wall instead of placed on top of the cabinet.