We have an only child who is now 13. We have never had any regrets. I hated being pregnant. I hate having my attention divided--even having a cat and a baby at the same time seemed like too much! I love that I still have time for my career. I love that we have the resources to devote to doing extras together as a family and nurture DS's passions. He is a happy, social, adaptable kid with no signs of being spoiled. We live in a neighborhood with lots of kids and he spends most of his free time roaming around with the neighborhood kids--I never worry that he is lonely.
Where we live, onlies are very rare. People in our town seem to assume that the only reason for having an only is that "something went wrong." In my mind, wanting one is as healthy and normal as wanting more than one or none at all.