These two snowball methods are not the only choices, but they provide a good foundation on which to begin. You should adjust them to your own personal needs and circumstances.
You might have a debt with neither the highest interest rate nor the lowest balance, but it's a balance you would want to pay off first. For example, if you've borrowed money from a family member, you might want to pay off that debt first to keep family relations running smoothly. Take whichever of the two methods fits your style best and adjust it if needed.
In the end, the most important issue is to make sure you begin reducing the debt. Take a good look at your personality and decide whether you are more rational or emotional when dealing with money. While you want to choose the most efficient method of debt reduction, you need to make sure that the method you choose will work for you until all your debt is cleared.