Ok, you guys are gonna hate me (probably) but I'm honestly gonna recommend that you start with Arch.
Before you castrate me, hear me out on this one:
-Yes, the Arch install is a f*cking pain in the ass x100.
-Yes, you will type in some commands and have 0 idea what they mean and do
HOWEVER
If you want to learn about UNIX, the basic commands, and just learn how your computer works (how it boots, what is an EFI partition, what does all this sh*t mean/do) then there is no better way to learn than to do it yourself.
So with that said, here's what I recommend you do.
Step 1: Get a new/wiped HDD that you don't give a sh*t about. (there's a very good reason for this, you might f*ck up and accidentally wipe it, or have to wipe it after you f*ck up).
Step 2: Unplug all the other drives from your system before you start (this reduces the chance of you wiping a drive you didn't mean to, it's easier than it sounds).
Step 3: Follow this guide on YouTube. https://www.youtube.com/watch?v=MMkST5IjSjY
Step 4: THIS IS IMPORTANT!!! In order to actually learn anything, you can't just blindly type in whatever you see in the video. GOOGLE EVERYTHING. Does he type in a command and you don't know what it means? Get your laptop or your phone and google that shit.
It's a time consuming, and daunting process for a noob, but you'll learn a lot and I highly recommend it.
Good luck!
EDIT: The arch wiki is also an awesome resource. You can find it here: https://wiki.archlinux.org/