When comparing Pantheon vs XMonad, the Slant community recommends XMonad for most people. In the question“What are the best window managers for Linux?” XMonad is ranked 3rd while Pantheon is ranked 21st. The most important reason people chose XMonad is:
XMonad is written, configured, and fully extensible in Haskell. This means that users aren't limited to a small set of pre-programmed layouts and actions: anything can be programmed into the configuration. It's simple to modify basic settings, and the example config has lots of comments to get you started. Haskell keeps this code clean, concise, and readable, and its type system keeps you safe from any serious mistakes. This makes it fast and light, even on very small and slow systems.
Ranked in these QuestionsQuestion Ranking
Pro Simple, clean aesthetic
Nonintrusive and easy to overview workspace.
Pro Smooth, subtle animations
Nearly everything is animated, but it's not over the top.
Pantheon is light on system resources, giving it the advantage of being able run well on a multitude of setups.
Pro Looks amazing
Looks absolutely amazing. Very nice to use. Amazing UX.
Pro Splitting and animations
Switching between workspaces is fluid, pulling up the workspace preview bumps up the rest of the desktop, open windows show up on the switcher along with larger icons, and everything is subtly animated. You have two windows taking each half the screen by dragging to corners.
Pro Highly modular
While built to be integrated, Pantheon is also highly modular. Shell components like the Panel, Dock, and app launcher can be swapped out with limited repercussions.
Pro Great for minimalists
Although you cannot put icons on desktop, it comes with very low number of pre-installed softwares.
Pro Perfect for chromebook
It's light and easy.
Pro Slick, smooth desktop environment
Easy to use and easy to configure, there is almost nothing that the developers did not think of to creat a top-notch user experience.
Pro Fully extensible with Haskell
XMonad is written, configured, and fully extensible in Haskell. This means that users aren't limited to a small set of pre-programmed layouts and actions: anything can be programmed into the configuration.
It's simple to modify basic settings, and the example config has lots of comments to get you started. Haskell keeps this code clean, concise, and readable, and its type system keeps you safe from any serious mistakes. This makes it fast and light, even on very small and slow systems.
Pro Efficient to use
XMonad is a very minimal and efficient window manager, especially if the user is familiar with Haskell.
Pro Very stable
Use of Haskell, in conjunction with smart programming practices, guarantees a crash-free experience.
Pro Handles multiple monitors well
XMonad can handle multi-monitor setups by default.
Pro Absolutely minimal
The entire window manager is extremely small, and includes nothing beyond basic window manipulation and tiling. Out of the box, there are no window decorations, status bar nor icon dock; just clean lines and efficiency.
Pro Highly configurable
If you enjoy programming, you can even add features to XMonad to make it your perfect desktop environment, and the Contrib modules give you most of what you need to do exactly that.
Pro Edit configuration and reload on-the-fly
Configuration is compiled into the WM, and it can be changed/updated on-the-fly, without requiring a full reload.
Pro Great availability of libraries
The use of Haskell as an extension language means that popular pieces of functionality are easily shared and widely available as Haskell Libraries. Many default layouts, and tools for quickly and easily building your own, are available through XMonad-contrib, and highly re-usable configurations are commonly shared through blog articles and the Xmonad Wiki. The documentation in XMonad-contrib is very clear and easy to read.
Pro Xinerama support
XMonad has full support for Xinerama: windows can be tiled and managed across multiple physical screens.
Pro Dynamic Tiling
XMonad uses dynamic tiling which means that it automatically handles arranging your windows into various layouts which the user can cycle through.
Pro Intuitive model which separates "screens" and "workspaces"
XMonad separates screens and workspaces. A screen "projects" a workspace. You can put a window to a specific screen, regardless of which workspace is currently projected onto that screen. This is more intuitive than other WMs e.g. i3, which only has the notion of workspace but not "screen" and requires you to remember workspace numbering. It is especially beneficial for multi-monitor setups.
Con Few configuration options
It is pretty bare-bones on a stock install, but further configuration options can be added through various official tweak tools.
Con Too simple
Good for people who want a plug and play simple Desktop Environment. But for a multitasking / entertainment / cutting edge or Gaming Rig this is not the answer.
Con Not ideal for enterprise environments
As it has no set release date, and no set support and/or EOL dates, that makes it a not so good choice for enterprises managing a number of machines where such dates are important to know before hand.
Con Slow maintenance
Any significant updates come with new release, which usually takes 2-3 years. Hence gets obsolete with current software.
Con Not available for major Linux distributions
Con No icons on desktop
Con Uses GTK
Nowadays, GTK is designed with GNOME, and only GNOME, in mind. Non-GNOME applications which attempt to utilize it suffer as a result. Pantheon is no exception.
Con Looks and feels like a Mac
Which may turn quite a few people off with the aesthetics, of course for some people, this is a pro.
Con Steep learning curve for uninitiated users
Like a lot of tiling window managers, the learning curve for XMonad is quite steep.
Con Requires a lot of Haskell dependencies
XMonad depends on GHC (the Glasgow Haskell Compiler) which can take up about 700 MB or disk space.
Con Requires knowledge of Haskell for configuration
Understanding of Haskell is required in order to configure XMonad.