As both a dog and a cat ow er - dogs are much more interactive, they're actually your companion, while a cat is just an unwilling roommate that kinda tolerates you cause you feed them and house them. Being pack-animals, dogs thrive on having a relationship with other members of their pack, i.e. their owner. Cats are thoroughly self-sufficient so people are exilarated when a cat decides that you can pet them for a couple of minutes.
On the other hand, that's why dogs are more dangerous and you have to work with them, which most people don't do, so it leads to shit happening. Also, being able to actually hurt you by their design, unlike cats.
Both really cool, tho, just in different ways.