Greetings,
I am new to this and I hope I this message assoicates with this group. I am in search of a good watch dog for my house. It's been years since I have trained or taken care of a dog. What type of dogs make good watch dogs and are least likely to be over aggressive to humans? My second question is where should I purchase from a private owner or from a pet shop ?
G. L.

you should never buy from a pet shop as those puppys are all from puppy mills. you can google Prisoners of Greed to learn about them.

reputable responsible breeders out there are few & far between. puppies are BIG business & most are just after your $$

have you considered looking at your local shelter? there are also rescues, a lot of them are listed on PetFinder.org

really what you need is something that will bark.

is there some reason you are thinking puppy?

Thanks for the response. I will begin looking at the places you listed. I thought it would be better to get a puppy and train him/ her veres getting a dog that was already use to another surrounding. What do you think ? Are boxers good watch dogs ?

[wishbone]

Boxer is having high energy level, bouncy and playful and it is a even-tempered, stubborn and strong dog which makes an excellent watchdog. It is a good dog for competitive obedience. Generally the female boxer dog may get into fights with other female dogs to display dominance. The training should start at the younger stage which is to be firm and consistent.

Check also the list from Wiki for some guard dogs:

Guard dog - Wikipedia, the free encyclopedia