Linux

I'd go with XFce. I have it installed on many old laptops that I have given away to my cousins, nieces, and mom. Works like old Windows if you modify the panels (remove the bottom dock, bring the main panel down), and then you put some sane defaults, like setting up sleep (NOTE: you will need to edit a file to make xfce go to sleep unattended), enabling natural scrolling, enabling the login manager to show username so they don't have to type it every time, etc etc). But after all that is setup once, xfce is the best case for an old laptop.

I highly recommend fedora kinoite for people who don't want to do maintenance or don't know how.

It being immutable makes updates incredibly easy, and makes it much harder to break the system, and kde is best for people who are familiar with windows.

Whoa, that's a lot of comments. Thanks for your suggestions, guys. I will think about this.

As other have said, please do an SSD swap.

If it's "unbearably slow" that is an indication of drive failure especially on old boot drives. Linux will not fix this.

After that, Cinnamon if they like windows. Gnome if they don't or don't care.

Pop os is a great "fire and forget" OS for normal users. I work in a computer shop and have seen tons of not-knowledgable people run it without issues.

Fedora Budgie desktop edition and keep automatic updates on

I think MATE is the best balance between lighter weight and ease of use.

Disclaimer I am on Fedora Kinoite with soon Plasma 6 too.

Staying in an older Fedora Kinoite version will spare you from the breaking changes. Like currently 38 instead of 39. I would use ublue kinoite-main. You can disable animations, baloo etc. and have a very minimal experience. (Kinoite is way lighter than Fedora KDE and doesnt even include Gwenview, Okular or Kate)

Have a look at EndlessOS. Easy Desktop, immutable Debian base afaik. VanillaOS also has a Debian variant.

Immutable stable Distros are really needed. But I think Fedoras rpm-ostree is currently better, because it uses a git-like approach. I also think it is overcomplex and moves too slowly, so I imagine something may surpass it.

Automatic upgrades like traditional distros are not enough (they only annoy users but dont really apply them), you need really automatic ones.

Ublue has ublue-update on some editions, which is really nice. Fedora wants to implement some half baked solution I guess. If your Grandparents are always at home and on power that is no problem though (metered networks, low battery, AC connected).

Linux Mint Debian Edition. Very windows-like + automatic updates = ideal for people who don't really want to have to learn anything new (assuming your parents are like mine in that respect).

Mint Cinnamon. I would choose Zorin Lite (XFCE) as it has nice theme already.

Gnome won't break. If you don't want them calling you up in the middle of a work day saying, "why did the bar at the bottom of the screen disappear!?" or "Berny, my screen turned black!", install Gnome

The Plasma desktop is well supported and is pretty close to a Windows experience.

I hate Gnome with passion because it's nothing like Windows. I tested Ubuntu 2009 and the Gnome DE is what made me not like Linux. I did not know at the time that KDE Plasma also existed

Debian is old and full of bugs. "Stable" means you are stuck with faulty, but known-state software. To have a carefree distro where you don't need to assist at all I recommend Bazzite (it's not just for gamers). Tested updates are applied automatically

Check out MX. It's Debian, but with tools to make desktop use easier. It defaults xfce, and looks quite familiar to windows users.

If the laptop's really old and low on ram, you'll probably need to use lxde/lxqt as they're a lot lighter.

I'd suggest installing something like discovery or software centre. It's really nice for casual users because it unites apt and flatpak updates.

For casual users I typically recommend using Cinnamon Desktop, it's the most Windows-esque UI and will be the easiest for them to pick up and use.

I roll with Cinnamon on Ubuntu and it's been extremely painless, very simple to get stuff do and shit just works.

I'd go with XFCE. Maybe Xubuntu?

Gnome is simple. Gnome is native for GTK apps, which are majority. You can turn on classic taskbar, turn off virtual spaces, add minimize button and it is now a classic user experience.

I don’t understand this obsession with Wayland vs X11.

On Arch I choose Gnome and the underlying technology is picked for me based on hardware of the machine.

I recall having X11, because I had nVidia card. I bought AMD video card and it started to run Wayland without any effort on my side. It was a while ago.

Arch would require you to make more decisions, which may lead you into the woods. Use Manjaro, which made Arch tech decisions for you like choice of network management stack.

I tried Manjaro last week on laptop. It has a polished user experience. Pick to use non-free drivers. Use Libre Office instead of free office. Install Firefox and chromium. Done.

Gnome just added full search and it is included in Arch and shall be in Manjaro in less than 2 weeks.

The advantage with rolling release for your parents is that you will never run install again. You will never need to upgrade version of Debian or Ubuntu. Just update OS every time you visit them, no more frequent than once every few months, not less than twice a year.

Manjaro has polished software installation experience at graphical user interface level.

If I'm not wrong, Fedora as stable release too will ship Plasma 6 in next month, they're doing tests now.

I chose KDE for my parent, because I know it well (I might have gone with cinnamon otherwise). It has paid off - every time they call me with a problem, I can immediately direct them to the solution without having to look anything up. Had to switch back to X11 though, because zoom was somewhat unreliable on wayland.

Why don’t you let them choose?

I would suggest go with LMDE. It is based on Debian 12 with latest Cinnamon DE. It would be resemble with Windows 90% of the time.

One word of warning about Debian, you may be already aware of this: resist the urge to add remote apt repos that replace packages that are provided by Debian (same package name).

It's ok if the packages are named differently even if they do the same thing, as long as they don't pretend to be the same package. One good example of this is the Docker repo, which gives their own packages different names from the Docker packages on Debian.

If the repo overwrites native packages you will eventually end up with dependency relations which cannot be solved by apt anymore (most often happens when you remove a 3rd party repo). This usually comes back to bite you after a couple of years when it's time to upgrade to the new Debian release – and you can't.

aptitude can sometimes figure out a way to straighten things out but it can involve uninstalling/reinstalling and then upgrading a huge amount of packages which is never fun.

Debian still ships version 5

Debian ships 5.27.5 - it's not just not updating often, but it's not shipping bugfix releases (latest 5.27 version is 5.27.11!). I recommend to avoid it and maybe look at KUbuntu LTS instead