I really liked how you sort of steered away from “fact” checking this and guided this claim to be more opinionated, which is what it is. There is a fine line between opinion and fact, and there is a distinction between facts associated with this claim (e.g. scientific reasoning on why dogs are physiologically more likely to be beneficial to owners) and defining what it means to be a “better” pet. From what I read, it seems that you think overall long-term health benefits of owning a dog are better when compared to owning a cat simply because dogs are more active. The person who wrote this claim, however, may not define “better” in such ways. However, you did include a credible source, being from Harvard Medical School, but that article never stated that dogs were “better than cats”, but rather stated many reasons why dogs are just beneficial pets to have in general. The article never compared cats to dogs, which is why I think this fact check is not very reasonable.