When comparing XMonad vs awesome, the Slant community recommends awesome for most people. In the question“What are the best desktop environments for Arch Linux?” awesome is ranked 16th while XMonad is ranked 19th. The most important reason people chose awesome is:
Awesome is highly configurable, allowing the user to change anything they see fit in order to make the WM work for them and their workflow.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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 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 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 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 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 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.
Pro Extensive documentation
It is sadly a very rare thing among tilling window managers to have comprehensive documentation, Xmonad is the exception to this rule as opposed to those like DWM, and BSPWM.
Pro Friendly community
Especially in comparison to DWM.
Pro Highly configurable
Awesome is highly configurable, allowing the user to change anything they see fit in order to make the WM work for them and their workflow.
Pro Low latency
Awesome was the first window manager to be ported to use the asynchronous XCB library instead of XLib, making it much more responsive than most other window managers.
Pro Keyboard friendly
Awesome is really keyboard friendly and you can do almost anything with keyboard shortcuts.
Pro Fully extensible with Lua
Awesome can be skinned, configured, and extended with Lua, a language with a programming model similar to the ubiquitous Javascript. Learning resources for Lua are fairly abundant, as Lua is a popular extension language, often used for scripting in games.
Pro Stable
Awesome always works as it should: it is very stable and reliable.
Pro Good default configuration
By default, you'll have a status bar (hidden in some modes), an application launcher, automatic fullscreen, manual fullscreen shortcut, etc.
Pro Tags instead of workspaces
With awesome, clients are organized with tags: one client can be on more than one tag, and multiple tags can be displayed at the same time.
Pro Some mouse tiling support
You can rearrange and re-size [some] panels via the mouse.
Pro Xinerama support
Awesome has real multi-head support via XRandR/Xinerama, with per-screen desktops.
Pro Any window can be full screen
Select the window. Hold ALT+SHIFT and press SPACE until the window takes up the entire screen.
Pro Easy module for useless gaps
Lain module makes useless gaps easy.
Pro Excellent user configurations available
For those looking to customize the window manager, some beautiful examples can be found on Github and the subreddit r/unixporn that put other window managers to shame in the sheer potential to expand and modify the window manager awesome has.
Pro Single window, multi-workspace support
The user can have each window visible on one, multiple, or no workspace. You can also temporarily include another workspace in the current one.
Pro Can create tabbed containers for yourself or use a user library
Lua opens the possibility of adding these "missing" features through one's own efforts or one of the user libraries available on Github.
Cons
Con Steep learning curve for uninitiated users
Like a lot of tiling window managers, the learning curve for XMonad is quite steep.
Con Requires knowledge of Haskell for configuration
Understanding of Haskell is required in order to configure XMonad.
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 Doesn't play nice with bars other than Xmobar
Though Xmobar is functional enough, it would have been nice to have a full compatibility to polybar, or at least for it to have more options for improving appearance.
Con Fragile haskell toolchain
Because of its very tight dependency on GHC, which doesn't have a stable ABI, trying to use distro-packaged toolchains can be a nightmare.
Con Has no really powerful layout like bspwm does
Although they have one with the same name.
Con Only tiling
No support for stacking.
Con You should have some skills to configure it
Awesome, like most window managers, is targeted at advanced users. Though is has sane defaults and easy to read documentation, it is still a far jump from the more common graphical UIs found in computing.
Con Messy configuration file
The config file is too long. The heavy reliance on modules (which you don't what each one does) makes it confusing for the user. And it is written in Lua. Combine these three things together and you get a ghastly monster of a configuration file.
Con Doesn't have tabbed containers
There is no option to have tabbed containers in awesome window manager.
Con Regular API breakage
Results in many of the scripts for awesome to be found online end up being outdated.
Con Updates break everything
There are substantial differences between versions, changing radical amounts of the window manager, that mean configurations need to be rewritten.
Con Pull requests for bug fixes take forever to get merged
Due to the number of devs required to do checks on the pull requests, they take upwards of 6 months before being merged into the main. This means if you need one of these features or fixes, you have to build from the source using that branch (which if you use the dev branch you probably already do).
Con Some programs don't cooperate well with tiling window managers
The user can usually work around this, but it can be quite annoying at the same time.
Con Configuration uses Lua (Programming Language)
It is time-consuming to make changes to configuration. Though Lua is a good language, a plain text file to configure things would seem to be a better approach.
Con Difficult to google for solutions to problems
Awesome is a very common word, making searches for solutions to problems using Google very time-consuming as a lot of chaff has to be sifted through.
Con Concept of layout sometimes does not fit what you want
The concept of layout sometimes does not fit what you want, for example, if you like the concept of layouts in tmux or in i3 - it works differently here.