Interesting.
As a middle child, I was kind of taken for granted in a way. Not in a bad way - just I was kind of independent and gentle. Apparently I never caused any trouble so I was just left there to be. My younger brother, who's the youngest, was definitely spoilt compared to the rest of us. He got a way with a LOT more than the rest of us could ever have. I think it was partly because my parents felt he needed some protection from the bigger kids :)
So was he spoilt? Yes for sure. Favourite? It's hard to say.
An independent, gentle middle child?....sounds a lot like my husband!
Yes parents do baby the youngest kids quite a lot...and let them get away with a lot! I think it's partly to do with the fact that by the time the youngest comes around they are too tired to reinforce rigid rules and just go with the flow a bit more.