Are you prone to motion sickness? If not, you might not need any of these meds. Most people do not get sick on Disney rides, even the motion simulators. If you are prone to motion sickness, sit in the front of Star Tours and other simulators -- the motion is less pronounced there, although the 3D graphics will be more "in your face."
Of course, my basic strategy is to plan meals after any ride that will shake me up or move fast. You can't get very sick if you don't have much in your stomach.