Mothers are excellent nurturers and fathers are great at preparing the child for independance. This is not to say that either is more important, that is what the judges and lawyers have been doing to American families for 30 years now. Currently the father has the right to shut up pay money (far more than he should have to pay) and see his child once a year.
Our system is so corrupt that since my divorce, if my ex-wife gets a big raise, my child-support would go up. How can that be considered fair by anyones imagination?
The ultimate is a good, healthy, moral man and woman marriage where the children learn by example (seeing a good moral relationship work the way it was designed by God).
These arrangements, based upon the factors above, tend to be realistic for the couple at hand. Whether their children are sons or daughters, babies or teenagers, the division-of-labor with regards to the caregiving of the children should be as nearly the same in divorce as it was in the marriage.
This is the only way to prize the stability interests of the children over the interests of either parent.
There are fathers who raise babies perfectly, attuned to every cue...a Y chromosome affects style, but doesn't diminish quality or importance. Trust me on this one.
A father should have no less time with his children in divorce than he did within the marriage. Ditto for mothers.
As to money, that is a secondary issue which should in no way subordinate the prescription regarding custody arrangements noted above.
Yet, it is an issue, so I'd say simply proportional division, based upon the real needs of the child. If Parent A earns $80,000 a year and Parent B earns $20,000 a year, the payment of "child support" should be divided 80% to 20% and put into a checking account that doesn't allow cash or debit/credit card withdrawals. Both Parent A and Parent B should have full access to the account records, and photocopies of checks written on the account should be mailed to both parents each month automatically, with the subject lines of each check noting the nature of the expense that the check is written for.