Others choose a style based on monthly dues. You may pick a particular style because a friend is already training there. Maybe the college or YMCA had a particular program available. For any of these reasons you may have no idea what other styles are. If you are looking to join a martial arts and you have several classes to choose from, remember, from a self defense point of view, all styles have their merits, but there is a lot more to consider than self defense.
Some styles emphasize breathing or meditation.
Others power and breaking ability, while some are sport oriented. If you have options, than use them. Call each of the schools. First ask what the monthly dues are and if a contract is involved. Cost and your financial situation can play a big roll in your chose of a class.