it is not only the size and shape of a fin, but also the position.
You can have more grip if you move the fins more to the end of the board, and if you like it looser more to the middle.
That is why we have the VFS (vario fin system) so you can have different grips with the same fins, just for what you prefer.
After testing many fins and shapes we found out that our boards (144 and 155)run best with 1.8 or 2.0 fins. This size will give you rfect grip in turns and overpowered situations but the board will be still loose for switching.