Having had both breeds you mention I can tell you they can be excitable, not good in a home protection situation. I now have a 110 lb black lab. He is the sweetest dog you would ever meet.
One day a guy on a motorcycle came down the drive, now my drive is 2 1/0's of a mile long, and Jake saw him as he got off. This sweet happy mass of a dog turned in to Cujo before my eyes. Hair on back went up and a single WOOF came out that was a loud very deep base tone I have never heard before. He pushed me out of the way with his body and stood guard at my feet. Now this was no small takes, as I am 6'4" and 260, so he was ready for a fight. The poor guy was just lost but he told me he thought the dog was going to kill him at any moment. Now, Jake never left my side and didn't yip, yap or carry on barking but that dog has a 6" gang of teeth and can run down a squirrel, pretty fast for 110. I know I wouldn't want that black ball of death after me. After the guy left, Jake was back in the grass, upside down waiting for the evil squirrels to return, a big black ball of 'holy crap what a nice day' dog.
Long story short, get a black Lab because remember you are not always around with the Colt Combat Elite 45 hanging at your side.