Linux

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..

GNOME

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.

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

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 the type of person who gets tired of a DE after using it for too long, so I'm using Budgie right now and I really like it. However XFCE is pretty nice, too, it's what I used to use.

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

i3 and never looked back!

@aMalayali KDE - desktop or laptop.

xfce since it came default with eos and its pretty lightweight

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.

Tried many, but Xfce won for me:

• great keyboard support (tiling windows, virtual desktops, etc.)
• doesn't get in the way
• compact re UI (don't like modern GNOME look with lots of whitespace)
• lightweight

And even though I use terminals a lot (neovim, git, etc.), I never stuck with tiling window managers in the end (e.g. i3). Rather I'm heavily relying on:

• virtual desktops (8 or so)
• manual window tiling via shortcuts
• tmux

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

If I want to use a graphical user interface, I generally use KDE Plasma.

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.

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.

KDE customize to how ever you like to use it!

I haven't tried Gnome since they trashed the UI ;) and I wasn't ever much of a KDE fan so the only desktop I have ever used since the demise of Gnome 2 is XFCE.

However I've switched back to Window Maker (a window manager) on my main PC and on my VM's and I may do so on my laptops too. I don't really need a desktop so to speak, I just use wmsystray to add a system tray and things like NetworkManager, bluez etc all end up there giving me what I actually do use of a desktop.

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

I'm really liking Budgie, can't wait for version 11 when they ditch the gnome libs/apps.

I recently switched to xfce.
I used KDE exclusively since 2004. That's a very long time but KDE Plasma in combination with nvidia got worse, what felt like, every single day over the last years, so it finally came to the point where I had no choice to look for something that works better.
Super happy with xfce after I set it up almost exactly like my KDE setup. Sure there are some thing that are not as "well rounded" than some of the excellent Plasma features but over all it works great!