What are some alternatives?
When comparing BusyBox X Pro and KingRoot, you can also consider the following products
King Go Root Checker - King Go Root Checker is a platform that enables the users to know whether root access such as Superuser has been installed on their device or not.
Magisk - [2018.12.8] Magisk v18.0 - Root & Universal Systemless Interface [Android 5.0+] Magisk
Root Booster - Root Booster is an application that enables the users to run their applications more smoothly without any delays, and it also improves the battery life of the mobile device.
Root Genius - Root your Android phone with just one click.
Kingo Root - KingoRoot for Android is the best one click rooting software/apk with highest success rate. Boost your Android Phone by rooting it with KingoRoot!
One Click Root - Rooting lets you take full advantage of your phone or tablet.