We never thought about Balham for our trip in London, but we must admit that it could be the best choice you can make to visit the city.
Nothern Line spreads all around the city. From Balham, it takes you to London in about 20 minutes, and if you don't go at the rush hour, you'll find a seat too.
The place itself it's quiet and really "English" , so this is one of the best place to feel like a Londoner and not a tourist, in my opinion.
Julie was outstanding as we felt to have a home in the city, rather than stay to someone's house.