If you have a yard anyone of the those dogs will suit you, as long as you give them the proper excercise needed, regardless if you have a yard or not. When it comes to protection instincts I would go with the Presa, mind you that Presas tend to have a sharp temperment, early socialization is the key. The dogo may need more excercise given thats its a hunting dog. The Dogo will do well in the heat as well. I am not a big fan of the bull mastiff as working quality dogs are hard to find. As a deterent the bullmastiff looks are enough to disaude any potential threats, they are not the best in the heat. I would suggest if you have limited living space, to get a pitbull or amstaff, staffie, a smaller bull breed which will do better in tighter living areas. Have you thought about an old english bulldog/leavitt bulldog? Hope this helps.