I agree that it's all about personal preference. When they take out the fat, they have to replace it with something, so you still have the same texture or consistency. That usually involves a lot of chemicals and starches. If you are counting calories, compare the various versions, such as whole, light, and fat free. Sometimes the calorie difference between the light and the fat free is so small, that it's worth it in flavor to go with the light.
My personal preference really depends on how I'm using it. Sometimes a fat free or light sour cream will do just fine. But sometimes, nothing can substitute for the real thing. In those cases, I just use less. Sometimes, I even mix
Usually, I would rather have a small amount of something "real" than a larger amount of an artificial substitute.