Rooting tools for Android devices vary based on the type of device you want to root and the type of rom installed on the device. Talking about Rom and Device Stock Rom Custom Rom Flashing a device with custom rom is easy than flashing one with a stock, to flash a device with a custom rom all you have to do is go to the Oracle of our age and search for you a root.zip file for your installed recovery model and flash the zip file either by switching off your phone and reboot into recovery or use a tool like flashify for that. Stock rom is a different story, you'll have to try different tools I've got some list here:

• KingoRoot
• iRoot I use the PC version of this to root my not too complicated device (MediaTek)
• Baidu Root
• King Root
• OneClickRoot But I'd recommend using the pc versions of those programs for more efficiency. Devices like Samsung are sometimes complicated to flash because of their extra layer of security Knox and configurations, to flash such devices you'll need to search for their root binaries and flash it using Odin or other related programs note this binary/files or rootkit are model specific flashing another phones model may end up leaving your device in a software brick. Hope this help.

I use Magisk. There are some good tutorials on YouTube that only take like 20 mins to follow.

If you want a very simple tool, I'd say SuperSU is the go-to tool. In most custom ROMs I tried, yet, it even is pre-installed, because it is so small and simple.

However, in case you want a bit more, and I am talking about easy to install plugins, fixes and root-apps here, then there also is Magisk. As far as I know it is based on SuperSU, but offers a lot more functionality, and if you want to get things working quickly and easily, it often is the best alternative to installing by recovery.

Relevant quick comparison