The real question... How to find the best dog for you.  Many people that take the steps to finding out which dog would best suit them ends up giving them a harsh reality. 

I've had my heart set on getting a border collie for a long time, just to realize that my busy schedule might not make me the best owner.  Apparently, me thinking they're absolutely adorable doesn't automatically make me a great owner.

There are things you need to seriously take into account.  

Activity Level:   Like I mentioned above, you need to take a SERIOUS look into your life.  Some dogs need MUCH more exercise and attention than others.  If you have a busy schedule, a small yard, and you're not a fan of giving your dog a walk, make sure to look for a dog with low activity levels.

Surroundings:  Keep in mind WHERE you are and in what situation you're in.  If you have children, are expecting, or plan on eventually being expecting, make sure the dog is child friendly.  If you have other pets, it's a good idea to make sure the breed is going to get along with the rest of the pack.  

Grooming:  If you don't plan on spending much money on grooming, and you aren't able to do it yourself, keep this in mind when selecting a dog. Some dogs obviously need much more attention paid to their fur than others.  People don't get Shih Tzu's to look as cute as they do just by letting their fur do what it naturally does.

Now, in conclusion, I ask only that you be honest with yourself.  If the dog you want doesn't match up in any of those categories, you might need to reconsider your choice in dog.  However, while some people will tell you to only get a dog that matches up perfectly with you, I say just to make sure that you don't get a dog you are going to end up having to get rid of.