I agree with zoom, you should consider an american bulldog. Also I was thinking a boxer...they're a bit bigger than what you're looking for, but they're great dogs. The ones I've met hae always been very friendly, they're great with kids (one of my exs was basically rasied by a boxer, I kid you not). And I know this is a little small and not quite as manly, lol, but a french bulldog maybe? Those are some crazy looking dogs...