Wow, Audi, BMW and the LS. That's a tough call.
I've driven all three a month ago, and all three of them are exquisite rides. If I was break them down, I'd steer towards the LS for Luxury, and Performance and Reliability towards all three.
For your family I'd go with the LS, unless you live in a snow state like a lot of us. Then I'd think about the Audi w/AWD.