A dog is man's best friend. That's what everyone who has had a dog before will say. I personally don't really know because I haven't had a dog or a cat before. People really spoil their pets. Spending money to give them organic food, grooming sessions, expensive bed for pets, etc etc.
I once had a turtle. But I don't think that really counts. Turtles don't exactly react back to you. I'm having a fish now too and well.. its a beta fish so its a little more responsive than a regular fish but still.. I think its safe to say that's its a little bit different than having a dog. Or a cat.
Can't exactly buy expensive luxurious items for a fish. Or maybe you can. By giving one small fish a 10 gallon tank. Hahha..