More children

My husband and I always wanted at least four children. We have been blessed with two boys already, (aged four and two) and had no trouble conceiving or during the pregnancy. We are trying for baby number three but I'm drawn towards the idea of fostering children instead. My husband isn't, he would rather complete our family with biological children and consider fostering later in life.

Is one option better than the other in your opinion? What and why?

Have any of you fostered and regretted it?

I don't think I could ever regret having more biological children once I fell pregnant, children bring so much joy!

Also to note, although we aren't super well off, our children have everything they need.