Practically, one of the main reasons that people choose a certain art is because it's offered near them. No matter how great a certain art is, if there's no school near you, you can't do it. Also, many martial arts schools focus primarily on teaching children, and may not have a strong program for adults. Then you have to look at what those adult programs are, and if they'll meet your needs. If a school offers, for example, Tai Chi classes, but you're looking to learn immediately useful self-defense techniques, that might not be a good fit.
If you want some help in choosing a style, I'd suggest that you start by making a list of some schools that are convenient for you to get to, and also a list of what you're looking to get out of martial arts classes. If you post some links on here, we can check out the schools websites and see which ones look like they'd meet your needs.
Most schools offer a free or low-priced trial program, where you can take a few beginners' classes without committing to anything more. That will give you a chance to try the school out and see if you enjoy it and it's a good fit.