Actually logarithm to the base 'e' is called natural logarithm because it appears naturally in terms of the logarithmic series. On the other hand, numerical calculations with respect to the base 10 is easier to handle in comparison to logarithms to any other base. That is why in numerical calculations, we use logarithm to the base 10.
The way I see, you should use Log(x) when you are working with powers of Ten. In engineering, it is very common, for example: miliseconds (ms = 10exp-3; Mhz = 10exp+6)