TAURUS: A turtle: it's slow-moving, doesn't need a lot of attention, and won't compete with its owner for food.
GEMINI: A talking parrot; need I say more? Well, of course, but--
CANCER: Anything, as long as it needs to be nurtured
LEO: A big, bold, ferocious feline, as long as it doesn't compete with its owner's place in the sun.
VIRGO: Let's see, I have to get up at 7:30 to feed it, let it out at 7:45, at 10:00 I need to go to the grocery store to pick up three tins of food, which will cost £3.86, including VAT--
LIBRA: Hm, good question. One the one hand, a dog is active, affectionate, and companionable. On the other hand, a cat is pretty independent and won't require as much time and attention. Oh, I don't know. What would you do? Are you sure?
SCORPIO: A cat. Secretive, mysterious, and unpredictable? What's there not to like?
SAGITTARIUS: A horse, of course! Let's hope it's got enough stamina to keep up with me.
CAPRICORN: Do I have to pay for it?
AQUARIUS: A hamster. First, I've got to set up a detailed cage with tubes going from here to here, and an energy sensor--they don't make anything like that? That's okay, I'm sure what I come up with will be much better.
PISCES: Fish. When their owner forgets about them for weeks on end, they're easy to replace. If Pisces remembers to replace them...