As a fellow Southern Californian, I would advise you to consider travel time/how often you'd be willing and able to go to the store of your choosing. If you live in West Hollywood, you know it's going to be a pain in the ass to get to Topanga unless you leave in the morning. If you live in Woodland Hills, you know that getting to Beverly Hills is a nightmare, period. If you live in Calabasas and work in Brentwood, you can decide based on when you plan to shop.
I'm sure some of the more seasoned shoppers would encourage you to think about other issues, but for me, it's geography.