I've had both and you can't really compare them because they both have plusses and cons. Cats are much more fun and entertaining. Watching them chase strings and laser lights is hysterical. However, litter boxes are something I never want to do again...so gross no matter how many I tried. Yes, even those self cleaning ones are gross. Dogs take a lot more care and you can't leave them alone as someone else said and have to kennel them to vacation. Plus, some can be noisier and more destructive. However, dogs are easier to teach tricks and as someone else said are loyal and loving usually and some are good protectors. My dog suzi is very smart and sweet to all. She is not a protector though for sure. She has cancer now according to the vet though, so her time is limited, which makes me very sad. I don't want another pet for a while after Suzi dies.