ShihTzus are great. I've had a couple; they are small, friendly, adaptable, cuddly, although they are a little larger than Yorkies & Maltese. My daughter has also had a couple of ShihTzus. She got 2 of hers from ShihTzu rescue group in our area. Both were from families that had to give them up. They were housebroken, obedience trained.
I have a Bichon now. He's a good guy, but has a mind of his own at times and isn't as cuddly as the ShihTzus. He wants to cuddle on his own terms; he wants to lie a certain way & if I'm not petting him the way he thinks he should be petted, he takes his paw & pushes my hand where he wants it to be. lol Bichons are larger than Yorkies, Maltese & ShihTzus if size is a concern.