Collie,german sheperd,or newfoundland?

i live in the countrie and allready have a collie and a cat but living in the country i feal as though i should have some sorta watch dog my collies not that territorial and likes 2 be up staris,i dont want a dog that attacks random people or guests but is still protective and watchful AND will kill an intruder:),BUT still loveie,so all of these dogs are that but the collies not as watch dogie,german sheperds 2 territorial,and newfoundlands can be plain lazy. So which 1?