I like terriers in general because they age well and have a long life expectancy compared to other breeds.
I also like the terrier disposition.
We babysat our neighbor' family's female Yorkie years ago whenever they had to travel. The dog was amazing. Never needed a leash. She followed my dad around and wasn't bothered by us kids.
My dad was the one who decided to give me a Yorkie. We got the first one and then went back and picked up his brother. First time in our lives that we have had 2 dogs.