Right this very second, my son is my favorite child based solely on the conversation I just overheard in the kitchen.
Graham: Wanders in the kitchen
The Doctor: Why are you away from the table? You weren't excused.
Graham: Mom said I could be excused.
The Doctor: Who's the boss?
Graham: Mom's the boss.
The Doctor: WHAT?
Graham: Oh, and you. You and Mom are the boss.
The Doctor: But who's the biggest boss?
The Doctor: But who's the best?
Graham: Mom. Mom's the best.
He really had today's win sealed up earlier, when his sister called me "stupid Mom," but he went for a personal best by helping Lily put her 343 piece Lego set together before dinner, and throwing down "Mom's the boss" after dinner.
Now, since this conversation happened after dinner, there isn't much time left for Lily to steal the Favorite Child crown away from her big brother. Add that to the fact that he goes to bed much easier than she does, and we may as well declare the winner for the day.