Well according to me Ubuntu is the Best Linux distro. Not far from it is Fedora. But if you are a beginner i'll suggest to go with Ubuntu. But if you want to become very good at it, you should later on work on a non GUI version as well, called Ubuntu Server. Red Hat is also quite good but it isn't free I think.
If you want to learn Linux, then you need to give time and play with it.
Here's what I suggest:
1. Download virtual box, free software from Oracle.
2. Download Ubuntu, also free
3. Of course install the Ubuntu to your virtual machine
Don't worry about messing it up.
Just wipe the virtual machine, if anything goes wrong.
Just make sure your PC supports virtual machine.
4. Learn basic Linux file permissions to understand how the OS does it.
sometimes depends on how confortbale you are with setting up your system, some distro such as Ubuntu, Fedora, or Mint, are easy to install and maintain, others like Slackware, Arch, Gentoo, requires a bit more of knowledge to set up.
It depends on your user profile. From "keys pusher" to software developer. Obviously, if you were developer you wouldn't be asking this.
I'm a "key pusher " (some daily internet navigation, some mail, etc and, in my case, a lot of spreadsheet wich are OS independent) and I began from zero with Ubuntu. It seems a lot as Windows in easiness for install OS and later, for software install and uninstall (It has a software center). From Gutsy Gibbon to Saucy Salamander and still here
Learn how to navigate the file system, with relative and absolute paths.
Learn to edit config file with VIM, also with relative and absolute paths.
Learn how Linux mounts drives and how to mount them manually, then access that drive through the mounted directory.
When you're feeling really bold go through the Linux from scratch project. http://www.linuxfromscratch.org/