We should never differentiate between our children because it might hurt the feelings of any of them who is not been dealt with as a favorite one. Every one from our children should be dealt with as a favorite child. Evidence in the authentic Hadeeths is for equal treatment for all our children with out any discrimination between them. There are Hadeeths guiding to pay more attention to our daughters and give them more sympathy and care, without hurting the feelings of of our sons.
Wassalam.