As many have said, there is no best style for a LE application. Every art will have its advantages and disadvantages. Try to pick a discipline that you are genuinely interested in and are physically capable of practicing on a regular basis.
If you're looking for a well rounded system, I'd honestly look into some form of MMA. You'll learn basic western/kick boxing, wrestling/grappling, and Jiu-Jitsu techniques that I've found work well on the streets.
Keep in mind that no matter what system you choose, you're only going to get out what you put in.