Canvas vs OnGUI

I want to create a simple module(like timer) that has UI and some code.
I noticed a lot of unity asset scrips in store draw their UI in OnGUI(). My question is, what is the more preferable way, to draw it in OnGUI() or use Canvas?

The new UI system, the one with Canvas, is far superior to the old system utilizing OnGUI(). The old system was not really appropriate to use in production titles.

Assets on the Asset Store use OnGUI() so much because it’s been around much longer. Going forward pretty much everything will use the new UnityEngine.UI system.