It's an easy decision if you ask us (dogs, natch) and Chris is on our side. But Liz is flying the flag for felines, so what does science say?
The deciding factors are tested tonight. Which of the species will prove to be more trainable, more independent, the best for our stress, and which understands us best. The final, and most important, question to be answered is whether our pets actually love us – and who loves us the most.
Cats vs Dogs: Which is Best?, BBC2, 8pm