When you have and love +/- 15 different kinds of chickens, and anytime someone talks about one type of chicken, you say, "Yes, that's my favorite, if I had to choose just one breed...." and then you know you're not telling the truth because you could NEVER choose just one kind to keep.
When every chicken you pick up, you tell her or him, "You're my favorite, I just love you the best!" And you really mean it, because there's no way you can pick your favorite chicken any more than you could pick your favorite child...