Yes, it is true, the Raspbian is the best OS for the Pi 3, and it is official too. You just need to dump the image file of the Raspbian on your SD card to install it on Pi 3. Though you may be a little bit confused person while using Raspbian if you are a first time user of Linux, it is the most popular Pi 3 OS in the world in which you will also get an enjoyable experience.

The Raspbian is a lightweight OS which is based on Debian distribution
It is specifically designed to work for Raspberry Pi devices
It comes with pre-installed software like LibreOffice, email client, etc.
It also includes a Minecraft special version to help you make something
You will easily find the guidelines and troubleshooting for Raspbian
There are dozens of videos available on YouTube also for the understanding and using Raspbian OS