The advantage of getting one from a shelter is that they are often put through many tests to determine their character and temperament, so you will know a lot about them prior to adopting them.  

Are they good with kids? Cats? Other dogs? Lots of people and activity in the house?  This will not be like getting a puppy and having no idea what its personality will be.  

The humane society shelters puppies that are waiting for you to give them a good home.  You may even find a purebred amongst the group. Choose carefully.   

Don’t choose a large breed puppy because he gives you the “sad eye” and then later find out that he barks all night to your neighbors’ dismay and your own misery.