The advantage to making a dog is that the dolls can do stuff with it (walk it, etc.) and I can do photo shoots of that. The advantage of making the hamster is that it diversifies the pets and I can do tutorials on making a cage and things. The advantage to not making a pet at all is that the house will be less full.
Violet is definitely going to get Rembrandt (who will be renamed Sam), and the Blythes have Bella, so maybe the house has enough pets already. Which of these pets, if any, do you think will be the best one to make?