Hello,
I second Linux Mint for ease of transition from Windows. However, you would be doing yourself a disservice by jumping straight into another GUI rather than to learn (and further develop) the ins and outs of the Linux operating system. This is, of course, your choice. I don't know how interested you are in non-mousey-clicky stuff.
I like to explain Linux in terms of Lego. Say you download a Lego castle and install it on your system. Sure, now you have a shiny new castle to play on/with. Now imagine downloading the parts and arranging the Legos your way. Now that's a castle. That, my friend, is Linux.
Anyhow, I'm getting preachy-speechy here. If you are interested in learning, check out the first two (free) courses online from edx.org at https://www.edx.org/course?search_query=linux :
Introduction to Linux
Linux Basics: The Command Line Interface
Good luck!