Linux

i3 and never looked back!

xfce since it came default with eos and its pretty lightweight

DE: KDE & Cinnamon. WM: Awesome & I3

If you haven't tried them, I recommend giving them a try. They all have something to offer.

I don't use Gnome, for example. People knock on it a bit BUT a large group of people swear by it for workflow.

KDE Plasma is the dream for anyone who likes to tweak settings. I used it on my laptop for a long time and it is very convenient. It also manages power and monitor settings very well. In terms of memory usage it is now similar to XFCE.

XFCE is perfect for people who don't like change. It is a slow moving DE; tried and true.

Right now I am using LXQt. Not sure why I decided to do that. It looks ok. It is fast and light. That's it's claim to fame. It can be used with different WMs which is nice.

Are there any particular DE’s you like on a laptop, because of things like power consumption and efficiency that would not come normally into consideration for a desktop?

I can't say I've ever looked into it. But, I found that KDE handled things very well. I used my laptop for full workdays, getting 11 hours out of it.

sway, the i3 clone for Wayland. I'm really happy with it, even on my Intel iGPU + Nvidia GPU laptop.

GNOME, despite the critiques it receives it's the most polished one and the one that gives me less problems

GNOME

I3 and KDE

KDE

If there was a modern Window Maker, I would use that. I mean with a notification area and when I minimize Firefox or Chrome I don't get five icons in the corner and it works as a Wayland compositor and supports HiDPI scaling.

I'm a KDE guy and use it myself on my notebook, but GNOME with its multitouch gestures and polished (if a little inflexible) workflow is also an excellent fit.

XFCE minimal but good looking. You could also go for MATE or Cinnamon..

Tiling window managers like i3 are imho nice for laptops, since they do not waste any space and can be easily controllen via keyboard. Takes a while to get used to them, however.

I'm the weirdo over in the corner using TDE (Trinity Desktop Environment, forked from KDE3) on both my desktop and laptop.

KDE customize to how ever you like to use it!

Gnome hands down has the best laptop experience. If you follow the intended workflow of using tiled windows and many workspaces. You can get to a very large number of windows, without getting lost, even with just the laptop screen.

Additionally the paradigm does translate well to a desktop for the times you are docked.

@aMalayali KDE - desktop or laptop.

i3
the less I need a mouse on a laptop, the better

edit: ok, you specifically asked for a full fledged DE and not just a WM. well, I picked what I needed and with Manjaro i3 as base, I had a nice place to start

I like Enlightenment. It uses 400 MB of RAM on my old laptop/

I recently switched from i3 to hyprland and quite like it. Wayland still has some issues, but the better scaling makes it worth it.

I went with i3 (i3wm) instead of a full DE on my debian laptop. I wanted to minimize trackpad use without requiring peripherals (like a mouse).

On one hand it's highly performant and easily configurable; on the other hand, it does lead to problems that I wouldn't have known about with a DE—for example, I had screen tearing for months until I learned I needed a compositor, which doesn't come included.

In other words: it is a very barebones OOBE, and requires a lot of setup and RTFM (it's probably in the user guide that i need a compositor), but the reward of higher performance/lower power draw, easily configuring the hell out of it, smoothly navigating everywhere with the keyboard alone, and reclaiming screenspace from taskbars and titlebars has made it my preferred setup (even on desktop).

Tangential to the question, but my "no mouse" ethic has taken considerable effort to learn the cli way of dealing with configuration that is trivialized by GUIs (e.g. volume and wifi, i'm still struggling with bluetooth and rtorrent), but it's made the experience of working on a laptop 500% more enjoyable and less of an uphill struggle against the trackpad, and it doesn't require a flat surface for a mouse.

Cinnamon for me, It looks like old Windows

Of the ones I tried, my top 3 would be cinnamon, budgie, and kde. KDE is probably the best bet for modern features ATM, cinnamon for simplicity.

On my laptops I like the same one as on my desktops: KDE Plasma. With any other I quickly start missing the features that KDE Plasma offers and the configurability and customizability. And It is also quite lightweight for all that it offers. Others often offer much less and consume more resources then KDE Plasma.

On laptops Gnome has a big advantage in the multitouch gestures for the touchpad, and as everyone says it's pretty polished. But lately I've been using KDE since it offers a lot more functionality and customization out of the box. Most of it's apps are like a swiss army knife and I love that. KDE is also catching up in the multitouch gesture department.