I really liked dogs growing up, but after having several cats as pets, I have come to admire them too.
To be honest though, I wouldn't say it's as straight cut as having a preference for one over the other. Both cats and dogs have good and bad qualities, and more often it comes down to the personality and temperament of the individual animal, rather than its species.
I've had cats that were a pain to look after and not that playful, but I've also heard of dogs who are also a handful to keep, and who were very frustrating.
I've also been lucky enough to own some really adorable cats, and a very cute little puppy too... So choosing between the two is very difficult.
If was forced to pick, I guess I'd have to side with cats. Mainly because I currently own 2 cats and 0 dogs.
Also there seem to be more cats on the internet, which is a wonderful thing.
Having said that....