Depending on where you live, there may be a variety of styles offered, or
you may be limited to just one. There are some differences between the styles that may make one of them more appealing to you. However, make sure the style is practical i.e. it is a popular style danced in your area. For example, if you learn "on 2" and there are only a hand-full of "on-2" dancers in your city, you will not have many partners to dance with.

If multiple styles are popular, check out various instructors and various styles before deciding. Talk to various dancers, and decide "who you want to dance like". Pick your first style that way. As a beginner, learning multiple styles from the get-go is not recommended. Concentrating on one style will make you a better dancer faster. Different styles can actually confuse the dancer's timing, which is something beginners have enough problems with already. As an advanced dancer you may want to experiment with different styles, and see what "feels" better.

Remember, many dancers will be biased to their own style and believe that it is the best. There is no such thing as the "best" style. There are however personal favourites. It's up to you to decide which style is your favorite.