Thank you OP for that, but… why should we prefer this over uBlue’s work on streamlining this process?

i’d like to try gnome or kde plasma

I’m surprised to see that no one has mentioned the following yet:

"KDE Edition

In continuation with what’s been done in the past, Linux Mint 18.3 will feature a KDE edition, but it will be the last release to do so.

I would like to thank Kubuntu for the amazing work they have done. The quality of Plasma 5 in Xenial made backports a necessity. The rapid pace of development upstream from the KDE project made this very challenging, yet they managed to provide a stable flow of updates for us and we were able to ship good KDE editions thanks to that. I don’t think this would have been possible without them.

KDE is a fantastic environment but it’s also a different world, one which evolves away from us and away from everything we focus on. Their apps, their ecosystem and the QT toolkit which is central there have very little in common with what we’re working on.

We’re not just shipping releases and distributing upstream software. We’re a product distribution and we see ourselves as a complete desktop operating system. We like to integrate solutions, develop what’s missing, adapt what’s not fitting perfectly, and we do a great deal of that not only around our own Cinnamon desktop environment but also thanks to cross-DE frameworks we put in place to support similar environments, such as MATE and Xfce.

When we work on tools like Xed, Blueberry, Mintlocale, the Slick Greeter, we’re developing features which benefit these 3 desktops, but unfortunately not KDE.

Users of the KDE edition represent a portion of our user base. I know from their feedback that they really enjoy it. They will be able to install KDE on top of Linux Mint 19 of course and I’m sure the Kubuntu PPA will continue to be available. They will be able to port Mint software to Kubuntu itself also, or they might want to trade a bit of stability away and move to to a bleeding edge distribution such as Arch to follow upstream KDE more closely.

Our own mission isn’t to diversify as much as possible in an effort to attract a bigger chunk of the Linux market, and it’s with a bit of sadness that we’re letting this edition go. We focus on things we do well and we love doing to get better and better at doing them. KDE is amazing but it’s not what we want to focus on.

With Linux Mint 18.3, we’ll release one more KDE edition. I wanted this announcement to come before the release. It will hurt its popularity of course, but I wanted to give users time, either to react right now or to take their time, upgrade and adapt to this later on. I’m sure this edition will be missed and I hope its users understand our decision."

From this Linux Mint blog post*.

Note that this doesn’t mean that you can’t use KDE Plasma (or GNOME for that matter). Though you have to be aware that you’ll be on your own whenever something breaks. And if you have to ask how to change Desktop Environment in the first place, then I think that you might not be ready yet for such a ride. Instead, consider using a distro that actually does offer GNOME and/or KDE Plasma editions of its distro; the likes of Fedora, openSUSE and Pop!_OS come to mind.

Aight, I actually don’t know a lot about it, but I guess something that looks like an answer is better than none. So without further a due.

First of all, Nitrux is quite unique, so I won’t be able to do it justice regardless. However, I’d say that it being an ‘immutable’ distro with OpenRC and focusing on AppImage (over Flatpak/Snap) is the primary one. It’s important to note that Nitrux’ model doesn’t allow you to install .deb packages natively at all. So in that regard, it’s one of the less flexible among its ‘immutable’ siblings. It does offer great support for Distrobox, so you can install your debs, rpms and from the AUR etc if you so desire within a container instead; you can even install other desktop environments with this. Waydroid works. AppArmor is configured. KDE Plasma looks fantastic on Nitrux, but they offer even more spice through their Maui Shell.

(Manjaro keeps breaking itself for a laugth)

Are you perhaps using the AUR more than you should on a Manjaro installation? Just for your information; because Manjaro holds back packages for a couple of weeks, any package from the AUR might conflict with those ‘outdated’ packages and thus cause some breakage. If you really need those packages, then you should consider container solutions like Distrobox to resolve this. Note that trying things like installing a custom kernel won’t work through Distrobox.

So the main options probably consist of:

• Just plain Arch; archinstall has made it a lot easier to install. Furthermore, after everything is set and done, it can literally be Manjaro without outdated packages and less bugs etc, or actually whatever you would like your Linux installation to be. Setting up is the most daunting part though. Fortunately, the Arch Wiki does an excellent job in providing a resource at every set of the journey. Recommended if you’re not scared of setting up your system from a blank slate.

• Any other Arch-based distro, really. There are a ton of recommendations found in the other comments and there’s even more if you check out Distrowatch for Arch-based distros. If you kinda know what you’d want from a future system, but can’t be bothered with setting it up directly from Arch, then this might be recommended based on the specifics of your demands and to what degree existing distros align to that. For whatever it’s worth, I think Garuda Linux is an interesting option for those that want to move on from Manjaro. Similary to Manjaro, it’s opinionated on how your system is/should be configured. That’s why it’s also one of the few Arch-based distros (like Manjaro) that offers -out of the box- the means to rollback to a working system whenever anything unfortunate befalls your system, Garuda achieves this through coming pre-configured with Btrfs+Snapper. It should be noted, though, that Garuda is considered bloated by some. However only you can decide for yourself if their offering is bloated to you or not. So check out its Xfce edition -or any that sound interesting to you- for yourself, if you’re interested. If you think it’s interesting, but are still too much bothered by the bloat, then perhaps their Lite versions are more to your liking.

There are a lot of options beyond Arch-based distros. However, as I don’t know what made you gravitate towards Manjaro in the first place and what you’ve come to (dis)like since, it’s hard to pinpoint what exactly you’d like. If the AUR has been your main reason for using Manjaro in the first place, then it’s important to note that Distrobox also grants access to the AUR from any of the other popular distros out there. So you’re not confined to just using Arch(-based distros) unless you really need some custom kernel that is somehow only available in the AUR.

• If you checked out Manjaro for its unsuccessful attempt at providing a stable rolling release, then you should check out the most successful attempt with openSUSE Tumbleweed. It has a respectable amount of packages and enables users through OBS (OpenSUSE Build Service) to extend this significantly. Its installer offers the option to go for a minimal installation.
• If rolling release has scarred you, but you still want up-to-date packages, then consider Fedora. Huge community, AUR-like repo in COPR and once again a very respectable amount of packages make it definitely worth a mention. It offers the so-called Fedora Everything ISO (Network Installer) that acts as the installer for minimal systems.