Do you have a decided preference between cats and dogs? Which do you prefer, and why? Would you consider a roommate or partner who had a contrary pet proclivity?
Though everyone knows me as a crazy cat lady, I do like them both. I've never had a dog, but I like most dogs (except chihuahuas... I don't even consider them dogs, they're just yappy little monsters) and would like to have a dog in the future. I've always had cats, so they're more familiar to me. I like that they're independent, intelligent, and low maintenance. They're also cute and fluffy. I definitely like both dogs and cats, but I lean towards cats.
Almost all my friends are animal lovers, so they're a good mix of dog and cat people (and those who swing both ways). Though I don't really want a roommate or partner, if I did, their preferences wouldn't matter to me as long as they liked both animals and wouldn't mind living with them in the future. I have four cats now, and I plan to get a dog someday (definitely not any time soon, but maybe in 5 years or so). In fact, I know I wouldn't get along well with someone who doesn't like animals... we wouldn't understand each other one bit. We might be friendly, but a more serious arrangement just wouldn't work. Besides, I get annoyed and defensive when people criticize me for animal-related issues, and sometimes the only people who really understand are other crazy cat people. And I have plenty of crazy cat people as friends, many with more cats than me. So there. Don't nag me about having four cats, and I won't bring up the fact that you cheated on your ex with his/her friend, went streaking on the elementary school playground, got knocked up, and/or took more than 4-5 years to graduate college. Glass houses, people.
I would also like to point out that my house is nicely rodent-free, and I have four excellent bug catchers on hand. They keep my bed and lap nice and warm for me, and Yarmulke has alerted me to leaky windows twice. I may not be able to breathe through my nose half the time (a very mild cat allergy turns into a moderate cat allergy when multiplied by four, especially when a long-haired cat is around), but it's totally worth it.