Thickness for thickness, airfoiled stab will be stiffer.
To put it another way, an airfoiled stab with a typical high-point thickness of around 1"
will be lighter than a 1" flat plate.
On the other hand , an airfoiled stab with a very thin T/E will not provide much (needed) drag, and could well be a bit too abrupt in response.
As usual, it's never quite as clear cut as first it seems........