I would normally say the black bead head in #12 but last time out I threw everything except my fly box at them and nothing. I also had a an olive , which I never have any luck with , and gave it a try out of frustration. The olive turned out to be the only thing they would touch. I actually fished it till I lost it , landing every fly on that one fly. My favorite wooly bugger? Which ever one the fish like will be my favorite. I am now fully stocked on olives by the way.