Some context:

I'm just a student and I have been using windows from my childhood, but I switched to linux about a month ago. I install ubuntu on my main PC as windows was lagging a lot. My PC is a very low end PC so I taught to give linux a try. I then installed kde plasma environment on my ubuntu. And I am so happy with it that I would never switch to windows again.
P.S. I'm not a die-hard programmer or a hacker, I am just a common user with some python knowledge.

Linux has a lot of awesome features. Lemme list few of the notable ones.

Features:

• Completely Free :
  Unlike windows, Linux has multiple distros that are completely free.

• Customisation :
  Believe me when I say that Linux can customised to the fullest. You can customise every element of the operating system.

• Flexibility :
  If you don't like something in your Linux operating system , you can change it according to your preferences. You are not bonded to use the default softwares/packages.

• Runs better on low end hardware :
  Some linux distros have very low system requirements and can run perfectly on lowend hardware.
  I have a low end PC and windows used to lag a lot but linux doesn't.

and many other features...

Who should use Linux instead of Windows?

If you are a developer, there is a high chance you are already using linux, but if you are not, then you can give it a try.

Installing linux & other softwares can something cause some issues, so if you are good at troubleshooting or googling then you can give it a try.

If you know the basics of computers, then give Linux a try

Or you are just bored of Windows and like to tinker around with your computer.

Which are the most user friendly Linux Distros?

I haven't tried many distros but according to me , you can try Ubuntu for basic users. Or you can try Kubuntu, it has KDE environment & has a lot of customisation features while is still very user friendly.

After all linux is used everywhere from the high end servers to your android smartphones, so why not give it a try on your desktop computer as well.

TL;DR - Give Linux a try, especially KDE plasma environment (Kubuntu)