Here's my analysis, see if you guys agree.
The instincts are larger, the corners are more aggressive, the soft grip much grippier, requiring less hand strength. They are easier to grip and twist.
The hard **** allows them to be spun pretty easily, but the old style hard handles are better for this i.e. good for lots of low torque clean screws.
I think the shape of either is superior to all others e.g. Wiha uses 19th c handle shapes originally lathe turned. I like them, but they are no match for instincts. Note that Williams makes hard handled screwdrivers using Snap On old HH shape.
The soft grip models are prone to damage, the rubber can be torn or worn to shreds. They are also more difficult to clean. That said, they are easily to grip with oily hands than hard handles. And note that they can be effectively cleaned with non-petrol detergents like simple green or dish soap.
I have hard handles from the early 90s. They have almost no wear after many years of hard use. They are easily cleaned and scratches can sanded out. I would recommend them for industrial, institutional users i.e. people who won't maintain them, replace worn tools etc. they are professional grade industrial strength models.
Last, the new ACR Phillips heads are nice. My old HH don't have this feature.
For individuals, especially home users, I recommend instincts.suggest buying sets or individual in different colors to speed up selection.
