As you can see in the attached graph,

Did I miss something here? I didn't find your graph.

The cylinder is also going to have more water moving at the fastest speed possible in the cylinder (thus having the most momentum) compared with a hemisphere of the same volume.

But at the same time, increased speed causes an increase in friction, thus dissipating that momentum more quickly.

Another factor to consider is that the speed of the water against the the cylinder is the same no matter where you measure it on the walls of the cylinder, and in fact is the same as the maximum speed in the hemisphere, given the example you suggested of equal diameters of the two containers. In the hemisphere, most of the surface area contacts the water at slower speeds, that is, the closer to the bottom of the hemisphere, the slower the speed, reaching a speed of zero at the very bottom.

So, which has the greater effect: momentum, friction, surface area, or velocity? Muzza said each volume of water was started with "...equal torque". I take that to mean that each volume of liquid has had the same amount of kinetic energy imparted to it, and thus the same momentum. That leaves friction, surface area, and velocity as the variables, and chances are the retardation through friction will be a function of the square of the velocity (I don't guarantee this, but I think I am right) whereas the effects of surface area will be a linear function. If this is right, velocity will be the most important factor, and the hemisphere will have the lowest average velocity and thus the lowest friction and the least amount of retardation.

tanstaafl.