Great question. For me personally, definitely very positive for my practice and my development as a practitioner. But I should also point out that spiritual development as a layperson bringing up children is a little bit different than if one were a layperson without children or a monastic. And that is because of the difficulty of maintaining one's practice in the face of constant and ever-changing adversities. Not that I am equating having children as adversity, but with kids comes the fact that one's available time to practice, study, attend retreats is somewhat diminished. Maintaining daily practice can involve creative ways to keep some time free for bhavana and pariyatti. Not only is there an available time to practice issue, but with kids comes an ever increasingly more complicated and complex daily life dealing with the minutae of providing for and looking after children and maintaining a relationship with children and spouse (and/or ex-spouse in many cases). So from time to time, I felt as though I had to 'dig deep' and bring to the fore some of those qualities that are mentioned in the Commentarial literature. Strong determination, renunciation, metta, dana, patience,tolerance & etc. Not only does one draw on those for support and strength, one actively develops them in daily life.
While it is difficult, I have found the experience of bringing up children and practicing Dhamma extraordinarily rewarding. And I feel privileged to having come into contact with such incredible (and admittedly at times incredibly hard) opportunities to grow.
I can't quantify the benefit of having kids has had on my practice. It's just different. What I do tell people is that lay-life is not second rate by any means.
I hope that's given you one perspective. And if you have any further questions, I'm only too happy to assist.