JRT's, austrailina shepards, and collies are out, all too damn hyper, when left alone during the day they will tear your yard apart.
labs are always good.
I've had the best luck with chow-pitbull mixes. very good with kids, very clean, level headed and stable. but if you're asking about breeds on a bbs then you probably don't have the experience to train them properly so it would be a bad pick. also many obedience schools wont take pit-bull mixes as they get bad publicity, and don't always get along with other dogs.
I'd go with the lab if I were you, reasonably smart, cooperative, and fairly forgiving of mistakes made in training.