When comparing LXDE vs LXQT, the Slant community recommends LXDE for most people. In the question“What are the best desktop environments for Arch Linux?” LXDE is ranked 12th while LXQT is ranked 18th. The most important reason people chose LXDE is:
LXDE is a simple desktop without a lot of bells and whistles, this allows it to remain lightweight which helps conserve battery power and maintain its speed of use.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Energy saving and extremely fast
LXDE is a simple desktop without a lot of bells and whistles, this allows it to remain lightweight which helps conserve battery power and maintain its speed of use.
Pro Simple and straightforward menus
LXDE utilizes a XP like menu which is straightforward and familiar to many users.
Pro Nicely balanced between speed, stability and features
Pro The most lightweight desktop environment
LXDE is by far the most lightweight desktop environment, even topping XFCE.
Pro You can setup LXDE with the same look across different machines easily
Most of the configuration of LXDE is read from files. Consequently, you can store and manage these files in the same way you might manage other dotfiles, meaning that you can setup LXDE to your liking on a new machine very quickly and easily.
Pro Uses Openbox
Pro Designed for cloud networks
LXDE works well on lower end devices such as cloud computers or netbooks. it is able to do this because of its low CPU and RAM requirement.
Pro Modular
By taking advantage of the modular KDE Frameworks, LXQT is able to offer a modular architecture that allows the user to easily swap components.
Pro Lightweight emphasis
With a focus on being "light-weight", it is to KDE Plasma what XFCE is to GNOME: a familiar enough looking lighter alternative to the more fully featured environment that may work better on lower-end devices and for people who want as lean a system as possible.
Pro Beautiful GUI using Qt.
Pro Great for old and low-end devices
LXQt is unparalleled in its ability to run on the weakest of machines without a problem.
Pro Utilizes Qt
As the name suggests, LXQt takes advantage of the Qt ecosystem to provide a beautiful and performant user experience.
Pro Doesn't use GTK3
Pro Doesn't use GTK3
Cons
Con Doesn't look very well out of the box
But it is very customizable.
Con Deprecated
Development has moved to LXQt.
Con Ugly and horrble UX
Con Development has slowed
LXDE is slowly reaching End of Life, but will still receive new updates as long as GTK +2 is in use.
Con No compositor
In order to keep the system light weight and CPU/GPU non intensive LXDE forgoes a compositing program, because of this there will be screen tearing. Though a compositor like Compton can be added for those that want it.
Con Only halfway to GTK+3
Most of Xfce's components were built in GTK+2 and the upgrade process to GTK+3 was very slow due to the lack of manpower.
Con Uses GTK
Nowadays, GTK is designed primarily for use with GNOME and with only GNOME in mind. Trying to do anything else with it results in needlessly hacky, unattractive programs.
Con Openbox doesn't support Wayland
Con Problem with log in
"The session is locked" message is a frequent problem when working with Lubuntu.
Con Poor file manager
pcmanfm-qt is lightyears behind its GTK version.
Con Very limited in customization
Very few themes available, especially modern themes.
Con Multiple application sources
Which leads to an inconsistent desktop.
Con Ugly
Con Not a full desktop environment
Like LXDE or Xfce it is not a full desktop envirnment and is missing many utilities that need to be borrowed from other desktops which will bloat the desktop.
Con UHD screens hardly supported
DPI settings are not adopted. The readability, usability of this DE on UHD screens is not advisable. Fonts are not scaled at all.
Con Unthemeable for usual users
As all Qt desktop environments themeing is hard since you need to know C++ , there is a sideway using qss however its not as powerful as GTK, Enlightenment or Windows theming.
Con Depends too much on KDE
Even the programs/apps shipped with LXQt are from the KDE project. They don't have their own projects yet.
It's pretty similar to Budgie that depends on Gnome for almost everything.
Con Pcmanfm-qt needs gvfs
you can mount drives with mount, but pcmanfm uses gnomes gvfs to mount drives.
Con Missing Features = Lightweight
For the LXQT developers, lightweight is a synonym for missing features.
Con A lot of bugs
This is a very disappointing desktop environment, it's very buggy. Although there still is hope that these issues will be resolved.
Con Not quite ready for open deployment
In the current state, LXQT is a beta desktop that feels like a heavy alpha. A lot of the tools and underlying features are in a testing state, while the LXQT project itself has not had a gold (1.0.0) release as of yet.