Similac Sensitive RS is the best formula that I've used (two kids, many formulas along with breast milk).  It is thickened which really helped my son's spit up and it is easy to digest.  He is not fussy and has slept through the night since he was two months old.  Some people complain because corn syrup is the main ingredient.  In most formulas, lactose or milk is the main ingredient.  Hello!  Corn syrup and lactose are essentially the same (SUGAR).  They are both natural.  Corn syrup prevents constipation.  If you don't have lactose (and this formula doesn't) then you're going to have...