@ Gary,  I live in a condo in a condo with my wife and 2 year old son in Los Angeles. The wife feels safe in the gated condo with lots of neighbors, but we will be purchasing a house in about 2 years, and this is when I will want to add a family protection fod to the family.

I currently have a female AB mix.  She is a great pet especially with the baby, but would never engage a human.  On the other hand, she was made to hunt anything she smells or sees, and this is why I can't take her on any trail.  Last time I did, she disappeared for 4 hours, thought I lost her.

Her brother controls bulls and hunts boars in the south.  This is why I want to stay way from boar hunting breeds or any breed with that crazy urge to hunt and or catch.

My previous dog was a Chow?Pit mix male who was just about perfect. He engaged a few times to protect me when I live in East Los Angeles, although he had no training what so ever. He listen to me extremely well, and on long hikes (12 hours) in the mountains, I wouldn't have to say a word.  He would always stay close,even when I took a nap for an hour, I would wake up and he would be next to me. When he would take off after a coyote, he would only do so if allowed, and would never leave for more than 2-3 minutes.

I love crossed breeds the most, and hope to get a similar dog as my previous one.  

Once we have the house, he/she will be sleeping inside the house. Size is important and agility, stamina and speed is also crucial.  I am not into the barrel stocky body type, but more into the leaner, longer, taller muscular body type 25 inches at the shoulder, 90 lbs, and short hair. 

If you are aware of breeders that have serious established programs crossing some bully/mastiff types of dogs with other leaner, more athletic breeds, that might be a good place for me to start looking. 

Thanks