I think I finally got it. EUREKA !
You both are right as I originally suggested.
It all depends on what you regard as ' better ' !
The forward dive plane when rotates will create resistance. This point of water resistance creates a new pivot. The momentum in turn creates a ' fish-tail ' swing like what happen to sudden stopping of the car without the anti-lock brakes. So the front dive plane WILL produce both plane force & the fish-tail force, making it more efficient on turning. While this is true, the fish-tailling however will delay somewhat the recovery to go straight . On the other hand, the stern plane provides turn without fish-tailling but will recover faster to go straight after the swing.
In conclusion, if you have very small dive planes, you might consider front planes WHICH WILL BE THE BEST, sacrifying a little bit of delay return to straight line but it will start your turn faster without hesitation.
However if your model sub has larger plane, and you rather like tighter control, turn & fast recovery from turns, you might choose a stern plane AS YOUR BEST.