None of them. Baby formulas have come a long way and are now infused with all sorts of vitamins, minerals, and whatnot…but it’s just not possible for them to contain the same properties as a mother’s milk. Breast milk contains live cells and antibodies, varies in taste with the foods that you eat and changes its nutritional content constantly to meet your baby’s needs as he grows. Also, the vitamins and minerals in breast milk have a much higher bioavailability than those in formula — meaning more of them are absorbed by baby’s body. Formula companies are constantly advertising a new ingredient that makes their formula “more like breast milk,” but this same rat race has been in progress for more than a century.
If you need to supplement for a medical reason, rest assured that most major brands of infant formula are very similar to each other in composition.