Going back to work...harder than I thought

And I'm not even talking about the emotional part, when you first have to leave your child in the care of someone else. Even just the 'business' end is proving to be a lot more difficult than I thought.

How do I really know what is best for my daughter? How do I ensure that I'm choosing the best form of care for her when I go back to work, without letting cost influence my decision? How can cost NOT influence my decision? On first glance, it appears that a nanny for one child is almost double what it would be for public daycare. If money was no object, what would I pick?