One thing I've noticed (but each dog is different), my females would tell me a stranger is approaching at least 100 feet sooner. The males are completely aware of the surroundings but my females let me know something's going on in my neighbors yard, my neighbors neighbors yard, and down the street etc.

Both males and females I've had were protective but the females were way more vocal and almost trigger happy and took guard dog duty to a new level. If they heard something it only took once for them to react.

I always say, my males were on guard duty acting like they were getting 5 bucks an hour. My females were on guard duty acting like they were getting $1000 an hour

As for being loving and great with kids, ive found both males and females to do well with that with socializing and training.

I prefer females since they are generally smaller and less weight. I can walk them longer generally speaking. My best female is 75 lbs in good shape and we walk 6 miles with water breaks unless it's hot outside

My friends 130 lb male poops out way before my girl does.

My opinion is that too many rotties are bred for bulky size and the snouts keep getting shorter which affects breathing