My favorite fin for the serenity in weeds or Hatteras for non white capping wind is the Tangent Dynamic 42. I do have the 35 for when it's capping but in chop find the 42 a little steader and easier to turn. Roger and I have agreed to disagree on this choice.
My overall favorite is a fin that Roger has in his truck, a 66 cm something straight fin . I watched others doing duck jibes and great pivot jibes with this fin, and was able to do a good jib myself with it.