That may sound like a stupid question, as I used to have both!
But the cat came first, then the dog, then sadly none 
Then we felt healed enough to get a dog again and while he's amazing, he's also a very very very very crazy cocker spaniel and all I've ever seen him do is bark like crazy at cats that come into the garden.
I'd love a cat, and my DD1 went crazy over our friends one today.
It's never going to happen is it?