I much prefer cats. I'm not afraid of dogs, I've lived with both cats and dogs all of my life. Cats just have more personality to me. The dogs I've had seemed one dimensional. When I was young, I was attacked by one. I don't remember the attack though, and the dog we got to replace it was the best dog I've ever known. To this day, I have no idea why that dog did that.
I would say that prefer cats because they don't need that much attention but since you invest so much into a pet, I'm going with dogs. They're much more useful and can be trained to perform a variety of tasks.
I've had a few pet cats in my time. Dogs are just too high energy for me and take too much effort to look after. When a cat starts getting on your nerves you can just pop him outside and he'll entertain himself until it's time to feed him.