Linux

Install gentoo

I'm a fan of the uBlue distros Bazzite (gaming), Aurora (KDE), and Bluefin (Gnome and software devs). Other than that, Mint, Fedora, or Pop beta if you want to try the new Cosmic desktop

Show her some pictures or videos of DEs and see what she likes. If she's someone who likes to make it look the way she wants, she might get a bit more out of KDE than Cinnamon for example.

I have been thinking this for a while too and it's a toss up between Fedora and Debian for a regular user and if you are gaming then something like PopOS or Bazzite I would want someone non-techy using something that is not a rolling release distro like Arch.

Here are some tips once you have chosen:

You can change your desktop environment later.

If you do your install with seperate partitions for /home and others, leave 10% unallocated. Also make /bin about 15gb and /boot about 1.5gb. When you eventually run out of space, you can use KDE Partition manager to add the unallocated space to the partition you need, even if you set up encryption (gparted doesn't play well with encryption). You can install Partition manager as a package, you don't need to use KDE Plasma.

Using a drive mirror is a good idea. Maybe use it the second time you install.

If you want to use a cool filesys like zfs, just use btrfs for now (licensing issues). Ext4 will also work for desktop user needs.

If you go with Debian, you can add repos to your /etc/apt/sources.list file. But it is a one-way trip, so before adding sid, consider running your program in a vm. Non-free non-free-firmware and contrib are fine

I'd suggest 0 change at first : boot on a live USB then connect with her Web accounts (e.g. Firefox Profile) then get an easy win. Sure not 100% will work but she'll be 80% there in minutes. If she hates it, logout, reboot, remove key and that's it.

My recomendations: Opensuse Leap 16, Mageia 9, Openmandriva Rock and if You want to try a Rolling release Opensuse Tumbleweed, Openmandriva ROME

All the disteos With KDE Plasma

I would suggest whatever you pick, it should be a similar base to what you run or are most familiar with.

If you run something Debian based, you should recommend something Debian based. Fedora, Arch, etc.

The same is also true for desktop environments, if you use KDE, recommend KDE. If you run something not necessarily beginner friendly, recommend what you're familiar with.

At some point you're going to be asked questions, so the more familiar you are, the better for both of you.

So my standard thing with newbies is to suggest putting it on their old machine rather than dual booting. I feel most people will be amazed at how fast linux runs on their last pc and how slowly windows does on their current and if they dual boot it can lead to lazily keeping it booted in windows were as if the linux is available for web browsing and such it will help getting used to it. What I use I think is good for newbies. Its a lazy mans linux in the sense that it comes with everything you need out of the box. Its called zorin and its an ubuntu lts respin and once installed without doing any further tinkering you can rdp to a windows host, burn a disk, open and edit sound, image, and video files. along with standard web browser and libre office and such. I think most folks could go with it unmodified for most everything they need to do. Since its ubuntu you can add programs from the software program and update with the update program but if you feel the need to do like windows many downloads will have a debian linux option which when double clicked will work fine. also out of the box it has wine with play on linux installed so often times windows programs can be run by right clicking them and telling it to run with wine.

Why do you want to start a distro war?

Is this with the intent of trolling our community?

"Let many flowers blossom".