When comparing ShiftIt vs KWM, the Slant community recommends ShiftIt for most people. In the question“What is the best window manager for Mac?” ShiftIt is ranked 4th while KWM is ranked 25th.
Ranked in these QuestionsQuestion Ranking
Pro Easy to configure
ShiftIt is configured through a simple UI where you simply press the hotkeys you wish to map to a certain action.
ShiftIt is very straight-forward to use for most frequent usages.
Pro Open source
Pro Works in the same way that Xmonad & i3 does for Linux
For those who would like the same tiling window management of Xmonad and i3.
Pro Highly configurable
Using the config file (kwmrc) you can configure a variety of options including Window spacing and padding, borders, hot-key commands, etc... There are those who would say that the possibilities are limitless.
Pro Software is free and open source
Pro Windows respond very fast
Most users claim the tiling and splitting of the windows in KWM respond more quickly and more reliably than the only other known window manager of its type: Amethyst.
Pro Runs in the background
The application runs in the background. There is no indication that it is running except the automatic tiling of the windows. There is no menu bar icon or icon in the dock.
Con A little slow
Similar to Spectacle, but it has a few more features, such as being able to pick the size adjustment increments. Spectacle was a little faster, though. Repeated size changes or moves in succession can cause it to wait for it to complete.
Con Imprecise when readjusting sizes
Con Doesn't support moving windows between workspaces
There's no way to move a window to a different workspace with hotkeys in ShiftIt.
Con No longer being developed.
Sadly the developer has moved on to work on a different project (Chunkwm), so there will be no more updates for KWM. However the code works well; no matter what version of Mac OS X you are using.
Con Takes long to set up
You need to use the terminal and edit the configuration file in order to adjust it to the way you want. This might be a little confusing for basic users. But once you have it set, you can just copy the config file and use it on a multiple amount of machines.
Con You need HomeBrew to install it
Homebrew is required to install it. Takes more to get it work in the terminal to get it installed and working on your system.