My personal opinion, the house space and what kind of animal would be a critical choice. If you are living in small apartment or condominium, I can say you should go for the small breed of dog or just a cat or both and your kids deserve more space to be active and have fun around the house. Maybe
this article could be useful to decide what pet you want to adopt so as your kids will react good and play well with your pets.
In the end, you know your kids better since you raise them. My priority would be kids first then the pets.