Are Children’s Book Publishing Services Worth It?

I’ve been looking into children’s book publishing services, but I’m not sure which ones are actually worth the investment. Do these services provide real value in editing, illustration, and marketing, or are some just overpriced? How do you choose a provider that truly understands what engages kids? Are small boutique services better than larger companies? I’d love to hear from authors who’ve used them what worked, what didn’t, and what would you recommend?