I prefer dogs as I don't like the way cats are always lazing about I think you have more fun with dogs. I did have 2 cats though and they were great but I love dogs alot more.
Cats are alot easier to look after than dogs in general, but depending on what breeds you are looking at it could all change. Generally getting a pure breed will be hard and they are prone to health problems. I have cats because the idea of walking a dog everyday really put me off.