i hope you have alot of experience with dogs and are really good with aggression training. they are great dogs, but if you have any kind of aggression problem with either dog... it can be dangerous. you cant just smack a 230 lbs. dog in the face and say no bite:crazy: i saw a rott that was not abused but not properly raised and he was only 10 months. at about 100 lbs, he was a very dangerous dog who needs some serious work to break his aggression.
now that i said that, back on topic.
i personally love my boxer as a guard dog. he dose a great job and he can be tough looking too. but if you really want a big mastiff, my personal favorite is the
douge de bourdeax