Why is this always an either/or question?

Most people really just want a companion of some sort, and are perfectly happy with any animal that fits their specific life arrangements. It isn't even cats and dogs as a limiting factor because there are other animals that can be companions, they just night not be practical/legal everywhere; with the added caveat that not all of those animals should be kept by humans at all.

Do you know how many people have both cats and dogs? The numbers are hard to dig up, but you'd be looking at around a quarter of all pet "owning" households have both cats and dogs. I've never found reliable info on other types of pets in combined animal households, but I've seen plenty where just the companion animals included a bird or birds as well as cats and dogs. I've even known a few people with less traditional companion animals alongside those. Pigs can be great companions, and then there's the more exotic stuff like skunks and foxes bred pets. I personally think those fall into the "shouldnt" category, but they exist.

Each type has benefits and drawbacks on a practical level, obviously. But in terms of the ability to be companions, dogs and cats do it differently, but they both do it very well. Equally well, imo.

Now, I'm better with dogs. I can read their language easily, and that's a huge plus in terms of compatibility since dogs need more training than cats if they're going to leave your property. And, frankly, that's where dogs as a group are superior to cats, they're better at traveling with you. But I love them both as groups. Hell, I love my damn chickens that we have now, I'm one of those people that just loves the company of animals. But I've had cats and dogs, at the same time and separately.

If I could do the work necessary to take care of a cat or dog, I'd have both again. I miss my cats, and my dogs, every damn day. But one of the reasons we ended up with chickens is that I can do the work they need on a regular basis.