Looks VS Sustainability

Only one of my Jubilee girls has went broody and stayed committed. Another was "clucky" for a few days then quit. The new momma is my smallest hen. We call her Itty Bitty. Most would kick her out of their breeding program since she's a little smaller than the others, but I'm interested in keeping good traits in my birds just as much as I am in correct type. Temperament, being good mother's/Father's, protectors, layers..all as important as having the right "looks."