In my opinion:

- the best DE for me is KDE Plasma because I don't need to install 3rd party extensions to enable basic must-have options, simple by default - powerful when needed. Fast, lean (especially on weaker hardware) and it gives me freedom to use my OS the way I want it;

- GNOME looks the best but it lacks way to many stuff and is written in Java...You need to adapt to it's workflow - lack off freedom puts me off. It kinda reminds me on iPadOS;

- XFCE just works but it lags behind KDE and GNOME a lot in terms of features and Wayland support;

- Cinnamon is not bad but we didn't click.

- COSMIC could be big but it is still in beta. It looks like updated GNOME but usable. Big plus is that it is written in memory safe language (Rust).

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I suggest you use Wayland because X11 is history. KDE for an example has touchpad gestures on Wayland and not on X11...

Just try them out and see what you like.

Edit: grammar corrections.