I have a mini schnauzer, two schnoodles and a yorkie. The schnauzer is my second one (the first lived to be 17.5 years old) and my mother also has a mini schnauzer (and a huge fan of them.) We got our first schnoodle 11 years ago and mated her with the schnauzer (hence the second schnoodle.) The yorkie was an after thought.
The schnauzers are great because of their loyalty and friendliness. I don't see too much difference in personalities between the schnoodles and schnauzer, all exhibiting mostly the schnauzer traits. They are very vocal dogs and love kids.
The yorkie is our first and he is much more emotional than the schnauzers. I will say that he loves my daughter immensely and wants to be near her all of the time, moreso than the others...a true lap dog. He is far more dependent, but his cuteness makes up for it. As for a kid dog, the yorkie is great because he wants her affection all of the time, whereas the schnauzer is content just being in the same room as a person.
All three types make great pets. Hope this helps.