Any of the large, easy to use distributions should work just fine. I’d recommend a popular distribution because it’ll be easier to get help online. So consider Mint, Fedora, OpenSuse, Ubuntu and maybe Pop!_OS.
I think the main consideration should be which DE (desktop environment) she’d like to use. IMO the main contenders would be:
- KDE - Very configurable, nice looking, a bit heavy.
- Gnome - Simple and very opinionated, so not very configurable, a bit heavy.
- Cinnamon - Should feel familiar to Windows users, a bit faster than KDE and Gnome.
- Cosmic - A middle ground between Gnome’s simplicity and KDE’s configurability, pretty fast.
- XFCE - Very fast and light-weight, fairly configurable, but not very flashy.
Based on which DE she prefers, I’d suggest getting a distribution that comes with said DE by default, for the best possible integration. How do you figure out which DE she likes best? Put Ventoy on a USB stick along with a few different Linux ISOs. Ventoy wil let you choose which one to boot from a menu. You could get the following ISOs:
- Fedora or Ubuntu with Gnome
- OpenSUSE with KDE
- Linux Mint with Cinnamon
- Pop!_OS with Cosmic
- Mint or Ubuntu with XFCE
Download an ISO for each, install Ventoy on a USB stick and copy the ISOs to the stick. Boot into each ISO and play around with the desktop for a bit. When she’s figured out which DE she prefers, install a distribution that comes with that desktop.
I’ve been using Linux for about 25 years. I completely stopped using Windows at home more than a decade ago.
I do some volunteer work for an organisation that refurbishes old computers and gives them to people who can’t afford one. For the time being we’re using Rufus to bypass TPM and other hardware requirements so we can install Windows 11 on everything.
We’re willing to install Linux for people who want it, but unfortunately I haven’t seen that happen yet. Most of our customers have no idea what an OS is. A lot of people also need Windows for education or work. There’s a free course available that teaches how to use a computer and of course that is also Windows-only.
We helped one of our colleagues to install Mint on his old laptop, though.