Multiple, armed, etc judo is the best martial art for self defense for the average person.
I disagree. I believe knowledge in striking is a necessity when dealing with multiple opponents. Judo has striking preserved in Kata, but without sparring it's not of much use.
Krav Maga has much better tactics for multiple opponents and armed fighting. It's sole focus is self defense, there's no sport or spiritual development involved(unless you count psychological preparation in it).
"He who defeats himself is the mightiest warrior" - Confucius(I think)