When comparing Slate vs Notational Velocity, the Slant community recommends Notational Velocity for most people. In the question“What are the best power user tools for macOS?” Notational Velocity is ranked 11th while Slate is ranked 21st. The most important reason people chose Notational Velocity is:
The interface is clean and unobtrusive.
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Pros
Pro Extremely configurable
Slate is similar to Linux WMs like Xmonad in that it is nearly infinitely configurable. You can either use the default configuration file or just Javascript for very complex/dynamic settings. Slate also offers editing a ".js" or a ".slate" file for configuration.
Pro Based on hotkeys
Hotkeys can be set to re-size and focus windows, as well as activate layout presets.
Pro It's free
Slate is completely free to download and use, which is a great option in a field of Mac WMs that often costs money to use.
Pro Allows for tiling
Slate allows for customizing the config file in order to emulate tiling windows.
Pro Lets you set default layouts
By using a feature called "snapshots", users can set up different default window layouts in Slate that they can switch to and from on the fly.
Pro Window hints
Slate offers window hints which are an intuitive way to change window focus.
Pro Simple and minimalistic
The interface is clean and unobtrusive.
Pro Free
Pro Syncs with SimpleNotes or Dropbox
Cons
Con Project is no longer in development
Development is no longer active on this project as of 2017.
Con Hard to configure
There's no graphical user interface for configuring Slate, meaning it has to be done from the command line interface or by editing a config file. This makes it somewhat difficult and time-consuming.
Con Missing features
Unable to perform all tasks of software it was meant to replace.
Can not move windows between 'Spaces' (virtual desktops).
Con Video fail
Demonstration video failed to highlight any of the advantages of the windowing system. Or at least, the advantages were so subtly intrinsic that no-one who didn't already use the system could appreciate them.
Con Feels a bit outdated
The last release was from 2011. Although due to its brilliant simplicity in doing what it's designed for, some might think there hasn't been any need for an update, as long as it still works with the newer OSs.