What is the Best Martial Art for Self-Defence?

Type the name of any martial art into Google, and I can almost guarantee that before you're halfway down the page there'll be a question along the lines of 'is [blank] good for self-defence', usually leading to a blog post or forum thread extolling said martial art's virtue for self-defence (yes, the irony of this being one of those very same blog posts is not lost on me!)