Speaking from personal experience, the advantages associated with the unmarried/child-free lifestyle are mostly intellectual and practical (for example, relocating without dependents is orders-of-magnitude simpler than relocating with them), whereas the advantages associated with the married-with-children lifestyle are mostly emotional (so I imagine, having never given this lifestyle a try myself). So, the married-with-children decision resembles the mortgage-payoff decision, with both intellectual and emotional factors to consider.
Whatever you decide - good luck!