Being childfree means:

More money

Less stress

Probably your sex life is better, since you don't have to constantly worry about the kid waking up when you're trying to have sex

And the most important thing: If you are unhappy in a relationship it's way easier to walk away if you don't have kids. There are many married couples that literally only stay together for the kids.

Relevant article http://archive.is/PT8G1