Welcome to Linux!!

First of all I would like to pint out that switching from Windows to Linux can be easy or difficult based on your approach..
If you're approaching Linux using it the same way as Windows, you probably end up having some troubles.

They are different Operation Systems, thus they work in a different way.
You may find some similarities with Windows when using a famous Linux Distro, such as Ubuntu or Linux Mint, but at the end you will end up using the OS in a totally different way as you were used to.
For example: you won't browse the internet looking for a .exe to be installed, instead you will either open the terminal, check for a software with a command and install it with a different command (or use the software center at the beginning).

So for a better experience, try to approach Linux with an open mind and don't compare everything with Windows.

Second important point: you're coming from a Corporation owned OS to a Open Source OS.
Every single change in the Windows universe is controlled by a corporation, meaning that the end users have only 2 choices:
- accept the change and stay
- refuse the change and leave (most of the people refuse the change but stay, ehehe)
The first Microsoft goal is to create a Monopoly in the Desktop market, and for many years they succeeded doing that, you can clearly see that when someone say that need to use Windows because of "that closed-platform software" that doesn't run elsewhere.

GNU/Linux is totally the opposite way, it' Open Source, meaning that if you have the abilities you can go ahead and modify almost every single part to fit your needs! The distro manteiners and software creators actually encourage everyone to do so! (these modifications are called "FORK" )
So you're entering a world full of alternatives, possibilities and decisions that needs to be taken.
The Windows' "Shut up and take my money" mentality doesn't really work here, and the first approach can be quite disorienting, because some choices will affect the way you interact with your PC.

The biggest decision that you have to take regard this software (or collection of software)
a Desktop Environment

On Windows and Mac the Corporation behind the OS decide what is the right DE to use (and Desktop Manager and Window Manager), without giving alternatives.
In some cases you may end up having an experimental environment that can be either loved or hated by the en user (Windows 8 for example), but there is nothing to do about unless you hack the environment to modify it.

On Linux you will easily encounter a distribution that ships with different Desktop Environments (or without), so that's why you have many different names such as: Ubuntu (Unity), Xubuntu (Xfce), Lubuntu (LXDE), Kubuntu (KDE), Ubuntu Mate (MATE), Ubuntu Server (without DM,WM and DE), etc..

What's under the hood is still Ubuntu, but the interface will be different depending on which of them you choose (you can also install more than one and manage them with the Desktop Manager).

So a good start point would be either Ubuntu or Linux Mint (which is based on Ubuntu) as the base distribution, because they're the most famous and supported distributions since years, and then choose whatever Desktop Environment.
I classify them as follow:

Innovative and Experimental = Love it or Hate it:
Unity (Ubuntu)
Gnome 3 (Ubuntu Gnome)
KDE (Kubuntu, Linux Mint KDE)

More traditional and lightweight:
Cinnamon (Linux Mint Cinnamon)
Mate (Ubuntu Mate, Linux Mint Mate)
Xfce (Xubuntu, Linux Mint Xfce)

Lightweight as a priority:
LXDE (Lubuntu)

There are many others but this is a good starting point in my opinion, you can compare on youtube, there are plenty of videos about the subject.
here an example:
View video on youtube.com

I personally will go with either Linux Mint Cinnamon or Linux Mint Mate
IMHO these 2 are the best for a newcomer