Personally, I like dogs. However, I'm not at a point in my life where I could adequately take care of a dog (they do require a lot of care), so if I had to get a pet I would get a rabbit. Cats are just too bitchy. My roommates own a cat, and the thing is borderline retarded. There is no teaching a cat. If a dog does something wrong you put his face in it, yell at him, and give him a little smack, and he will never do it again. Or will avoid doing it at all costs. A cat, is well nigh impossible to train. Except they learn when to expect food.
And you should always adopt. Mixed breeds are usually more stable than purebred animals. And they are a lot less expensive. Of course the purchase price of most animals is usually the least expensive part of owning them.