Get the dog. I would get the dog but it depends on you as a person and you as a person on a budget.
If the cat is free, then by all means take the cat.
If the dog is free, then by all means take the dog, but I'm guessing that isn't the case.
My family breeds dogs, so that's why I'm saying.
If you don't have enough in a budget for the price of either animal pick the opposite.
It will make you just as happy I'm sure.
Personally I have a cat and two dogs and no one could make me choose between my kids, lmfao.