Im going to pick Brian i know stewies intellegent and perhaps is smarter than most of the family but hes only a baby.Brian has helped stewie out before now with somethings he just doesnt understand i admit Brians not built a time machine etc but hes plus clued up on life than stewie.Im not saying stewie doesnt know anything about life but not as much as Brian.
The Smartest person ou thing in that house hold would have to be Brain because he always know what he talks about even though he is only a dog. He is basically everyone voice of reason and is always right. And he also has a romantic cœur, coeur and knows what to say when a person is down. Sometimes he too does stupid things but thats only when he's in l’amour ou trying to fix a friendship ou trying to avoid something clearly stupid.