For english mastiff lovers!?

I would wait until your baby is walking before you make any decisions about a dog. It is NOT necessary for them to grow up together and as a matter of fact, puppies and small children do not necessarily make good companions, especially large breed puppies. They don't make good exercise partners because they often have heart and hip issues. They are lazy and like to hang out at home (preferably on the couch lol). All breeds have some dogs that have turned on their owners- sometimes it is an undetected health issue, sometimes lack of socialization, sometimes abuse. barring a medical issue, a well trained, well socialized, well loved dog will not turn on it's owner. especially if it is fixed. Honestly, given your requirements, I would suggest a golden retriever, lab, wiemeraner, or some other gun dog- they have lots of energy, tend to love the water, and are every bit as protective as a mastiff.