Mint is a good Linux choice for new Linux users. It has everything you need built-in. e.g., To play commercial movie DVD's you need libdvdcss2 installed. Most distros do not have this installed. It's trivial to install, takes all of 5 seconds, but a new Linux user man not know they need to install this, or how to do that. Mint has it installed by default.
But not just new users opt for Mint. That is the distro that I run on my main desktop computer. And I'm more of a Linux/Unix guru, not a newbie.
Arch Linux is an excellent distro. But Arch doesn't hold your hand quite like Mint does. I consider Arch a distro for moderately knowledgeable to advanced Linux users. Doesn't mean that a newbie can't use it, but it might be a little harder for them to. However, the online documentation for Arch is excellent. Many users of other distros go to the Arch documentation when they need to find out how to do something.
Arch is "leaner" than Mint. In their default configurations, Mint will use more resources than Arch. However, compared to Windows, even Mint is lightweight. If you have older/slower hardware, choose the Xfce desktop for Mint. That is the lightest standard desktop they offer. Next heaviest, but not by a terrible amount, is the Mate desktop. Heaviest is the Cinnamon desktop.
If your hardware is old and slow, you might want to investigate the antiX distro. That is quite lightweight. And it uses the Debian (another distro) repositories (where you download software from). Debian is a super well supported distro. Solid as a rock. Stable as all get out. Ubuntu (another very popular distro) is based on Debian. And Mint is based on Ubuntu. Since Mint has access to it's own repos, and Ubuntus repos, and Debians repos (may sometimes need some tweaking for certain Debian stuff) - Mint has access to just about any programs you could want. I like antiX, but I wouldn't call it a newbie distro necessarily. antiX has the most fantastic live boot persistence options. And a very nice thing called a "frugal install". These are maybe a bit advanced for the typical newbie to know what they are. But believe me, they are really handy features. Similar to antiX for persistence/frugal, is a distro named "MX Linux". It has more stuff installed by default than antiX, and might be easier for a newbie to sit down and be immediately productive with.
There are a bazillion different Linux distros. Don't get hung up on that. Linux is Linux. What changes between distros is mostly the GUI user interface and the programs installed by default. There are some differences "under the hood" between distros, but most new users aren't going to care much about that, or even realize that there are differences. When you fire up Firefox or Chrome for web browsing, or Thunderbird for email, you're not going to be able to tell which distro you are running that on. It looks and works the same everywhere. You would be hard pressed to even tell if you were running those on Linux or Windows!
Remember, "RAID is not a backup system". RAID is used to keep uptime as high as possible when dealing with hardware (disk) failures, and for speed - depending on how you configure it. For a home desktop computer, I consider RAID useless. RAID might be better suited for a home server in some circumstances. But then, ONLY if you already have a good separate backup system. If you don't have good backups already, use those extra disks for backup, not for RAID. I know many people who have set up RAID at home and when I ask them why they did that, they don't know. If you can't clearly state why you need RAID and what problem you are solving by implementing it, then ... you don't need RAID.