Many people call for a male. I always ask why? Most say for their size. Remember, our girls are larger than most back yard breeder's boys.
Boys are like rowdy teenagers the first half of their life. A male will squat wherever he feels the urge in your yard but a girl will go to the farthest place and do her business. If you do not remove it, she will leave another deposit right next to it.
Girls are clean like cats. They like their environment clean. It is in their nature. Their instinct is to prepare a nest for their pups. Mother Nature has programed a deep respect for the need to keep a clean nest. They will do everything possible not to soil their environment.
Plus, some males get very rowdy when a girl in the neighborhood is in heat. Tales of a male chewing through the drywall and out the exterior siding have been told when they are determined to pursue a female in season.
My boys are so obedient and attentive until they are taken over by the need to breed and they change dramatically. Ever try to persuade a 240# creature to resist it's primal urge? Difficult to say the least. The edge is removed somewhat when they are fixed but not completely eliminated.
Bottom line, a huge creature that goes temporarily insane makes for a long couple of weeks.
Females, not so much. Especially when they are spayed.
Girls are protective of their home. Not overly protective but protective none the less. Boys seem to not care as much. They fear nothing. There is no recognizable threat to them. They rule. But threaten the family and it is a whole other matter. Females are always cautiously alert.
No bad guy wants to tangle with a 200# mother protecting her family. You need a boy to procreate but when you weigh the pros and cons, I recommend a female for the first time owners of this majestic breed.