Answer
The natural logarithmic formula is used more because it's simpler when $a = e$ because $\ln e = 1$.
Work Step by Step
$\frac{d}{dx}(\log_{a}x) = \frac{1}{x \ln a}$
From the formula we see that the main reason why the natural logarithm is used is because the differentiation formula is simpler when $a = e$ (because $\ln e = 1$).
