Favoritism is a complicated subject in that the term itself hides family patterns. Yes, there are families in which some children are explicitly favored over others. However, what does favoritism mean? It’s not often clear. Is it more time spent with one child over others? More money spent? More attention? More excitement? Feeling more warmly? Shared interests? If it’s attention, negative attention can be effective in garnering more time. In that way, difficult children may be “favored,” if competition for time and attention are at the center. However, this report argues that taking a look at research on favoritism, that older children, girls, and more easily-parented children are favored. Maybe this is correct, but please keep in mind that child self-report (which many of the studies on this topic are) is a poor predictor of favoritism. In fact, most children are not good at identifying who is the favorite.
Link to a report on this research article:

