Female Dogs
Personality-wise there is really nothing different from a female dog and a male dog. You've got your dominant and aggressive female dogs just like you do males, and vice versa you've got your submissive and calm female dogs just like males. So when deciding if you want a male or female dog, your main concerns in terms of differences will typically be the dog's size, as females are generally smaller than males (not always but generally), and whether or not you want to get the female spayed.
Although, I personally think that unless you have the intent of breeding, you should get your dog spayed or neutered because it is overall healthier for the dog and you prevent unwanted pregnancies, but it is always up to you, the pet owner, as to what you want to do.
If you have decided upon a female dog, you'll probably want to brush up on some information about dogs coming into heat and what all a spay involves.