How do you pick just one?

Early one summer, we (my kids and I) decided we would like to get another dog.  We had had a Westie (West Highland White Terrier) a few years ago that we LOVED, but he had so many health problems due to allergies, we had to let him go.  I looked through many web-sites trying to find out which dog would be the best for our family.  One day, we were on our way to Sam's Club when we saw a family selling puppies out front.  Of course we went over to see.  They were the cutest little Imperial Shih-tzu puppies I had ever seen!  There were 5 left, all girls.  I had already decided that we would get a boy, they are easier and cheaper to neuter, and I felt like that would be a better fit for our family.  My youngest daughter was with me, and we went to look.  She was 14 at the time, and very quickly fell in love!  We held them for awhile, and then left to do our shopping.  All through the store, my daughter Ooohed and Aaawed over these puppies!  "I'll clean up all of the poop in the back yard."  "I'll feed her and bathe her and train her."  "I'll do any chore you want me to for the rest of my life!"  "I'll DIE if we don't get a puppy today!"  I have to admit, I was hooked myself, but they were going for $800, and that was WAY too much to pay for a dog!  Finally, I said, "Let's ask your sister what she thinks."  Her sister is very allergic to everything, and although Shih-tzu's are called "Hypo-allergenic" I thought we'd try it out, and see for sure. 
Sis showed up, and I was in trouble.  My normally angry at the world 17 yr. old had melted into a puddle of goo before she even picked one up.  Okay, I guess we're getting a puppy today, but how can we pick just one?  The owner started telling us about them.  There was a cuddly one, an independent one, a playful one, and one she called "the character of the bunch."  The character was also the runt.  Of course, that's the one my girls wanted!  We bought her.  I've never seen my kids so happy!  We bought dog supplies (I was not expecting to be bringing a dog home that day).  We picked out a name, Izzy.  We took her home and loved on her!  We got books from the library, and looked up everything possible on the internet.  Everything we read told us that Shih-tzu's are sedate dogs that need little to no exercise.  Most will sit contentedly on your lap, or in a sunny spot all day.  We were told that our dog would not like to be outside, so we should look into litter box training. 
Remember how I said that we brought home the "character of the bunch?"  My Izzy LOVES to be outside, will play fetch for hours (as long as you go get the ball), and is the silliest little dog I've ever seen!  She likes to fight and play, and get into all sorts of trouble!  Some days, I ask my kids, "Why is it again that we didn't get the cuddly one?"  Well, the cuddly one wouldn't be Izzy, that's why!