I browse several martial arts and self-defense oriented forums, and this same question comes up literally daily. Anyone interested in self-defense can find MILLIONS of web pages that say their "style" is the ultimate, the most practical, the coolest, the only true answer.
Bruce Lee realized two things:
1. As a race, we all have basically the same arms, feet, and head, and they all move more or less in the same way. The idea, therefore, that there should be a Japanese way of fighting or a French way of fighting is absurd. Truth in self-defense can be found anywhere.
2. As individuals, we all have unique talents, limitations, and circumstances. Therefore, some techniques that would be fine for Michael Jordan would not work well for Miley Cyrus.
The solution, then, is to create an approach that is based on principles that are universal which can be exploited to optimize to each individual's unique characteristics.
It's not about a best style at all - it's about the individual. Like I always say:
It's all about YOU!
~Jim