There are a few reason for this. First of all, I will get a plenty of attention from a lot of people esp. from the person I love.
Second, it needs only little care and concern. There is no need for food, cloths, medicine and love. As long as you dont pour water on it, dont open it when its raining, scan virus and clean sometime, it will last for several years. Its cost is pretty low compared with being a human.
Last but not least, , a computer does not have a feeling and emotion so that it will never be suffering by any kind of thought. It could be harmful by a wrong use, accident and virus (me too actually). But that is occasional. I think people love it enough and will never hurt it intentionally.
From what described above, I think I want to be a computer (LINUX, probably)
SOurce of the photo: http://www.shutterstock.com/