The personality of a dog is flexible and indeterminate. Dogs can be exuberant or shy; friendly or hostile; fearful or bold; aggressive or passive or some combination of the above. These differences in personality may to some extent be determined by breed, or individual genetics, but for the most part it is based on how and to what extent each particular dog has been socialized.
If you ever owned a dog when you were a child, you can probably recall the joy and exhilaration you felt every day, playing with your best buddy. Once you grew up and (assuming you) started a family, you probably wanted your kid(s) to experience the same things that you did. A loving, loyal, fun-loving animal companion is one of the best things in the world.
You may have felt that choosing a breed was the biggest decision you had to make before getting a dog. But now that you have made that choice, you are now faced with a more basic decision: do you want a male dog, or a female?