If you were to die with your dog near you, maybe you got lost in the woods or something, he/she would stay next to you until someone found you, or until he died with you.
Dogs for sure.
Not sure if someone said this already or not, but it's my reason.
I have a dog and a cat, but my favorite is my dog. Sure my cat sits in my lap when I play call of duty, but it doesn't actually do anything other than eat and sleep.
Dogs are better; they're mans best friend, cats are cool when they are kittens but when they're older they just disappear and come back when it's food time then they sleep.