I think a Boston Terrier, Corgi or my favorite A MUTT. You can usually find out how big a mutt will be if you are getting it as a puppy b/c the owner should know what the dog got pregnant by..and you can know what kind of coat they will have...I wouldn't get too small of a dog b.c they aren't as good with children by nature. Plus if your little ones are as rough as my boy the can accidentally hurt as smaller dog with finer bones. Also, All I know about Jack Russells is from personal experience and they are very hyper! Good luck!

shiba inu...dacshund.....westie.....chiwawa (cant spell) beagle