I don't have a favorite word, but I hate the word "tween" (when describing someone between the ages of 9 and 12) with the passion of a thousand supernovas. What is so wrong with using pre-teen, I ask you?
It's been a buzzword in the entertainment industry for the past several years, a neologism created by money -worshiping morons, often used by people who don't know better. It....displeases me. Never mind how I hear about it, All I know is I don't like it.