Rooster Origami Folding

Classical Mechanics Level 2

Suppose you start with three clean pieces of squared origami papers of the same density and non-zero paper thickness. Let $A$ be the smallest paper, $B$ medium-sized, and $C$ the largest. You are to fold each of them into a rooster as instructed.

Which piece of paper is the most difficult to start with for origami-folding?

Details and Assumptions:

Neglect deformation and paper-wetting during folding.
Assume that the folds are perfectly symmetric.