cat or dog person Watch
Both make great pets, I'm just more of a cat person myself :p both are loving, despite what a lot of people say about cats being unable to show or feel love. Neither are too expensive to have but I would recommend insuring them and maybe keeping some money away in case of emergencies regarding them.
Whatever animal you go for, I would recommend that you check out your local animal shelter instead of going to breeders. RSPCA, Cats Protection etc have animals from kittens/puppies up to adult animals and the adoption fee is usually around £50 and for that you get the animal spayed if they haven't been already, they are protected against worms and fleas and the money from the adoption fee goes straight to looking after the rest of the animals in the shelter. I've adopted all my cats as well as dogs in the past and they were never 'damaged goods' like a lit of people seem to think animals in shelters are. As they say - adopt, don't shop
This isn't something we can decide for you, getting a pet is a big responsibility! You've got to be prepared to look after it, spend money on it (food, toys, vets bills etc), take time out of your day for it (walking - if you get a dog, fussing and playing etc). Also consider whether your home is suitable for a cat or dog, both need space to roam around and explore, even indoor cats. Lifestyle is an important factor too, if you're going to be away from home a lot, then a cat may be a better choice than a dog as cats are generally more independent. You should get a pet because you like the animal and want to take care of it