When comparing Unclutter vs SizeUp, the Slant community recommends SizeUp for most people. In the question“What are the best power user tools for macOS?” SizeUp is ranked 57th while Unclutter is ranked 64th. The most important reason people chose SizeUp is:
SizeUp has user-configurable keyboard shortcuts for a set of pre-defined actions.
Specs
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Pros
Pro Convenient and fast access to files and notes
Unclutter lives in the navbar at the top of your screen, and is always accessible. Any files and notes stored in Unclutter can be quickly accessed from anywhere, with just a mouse movement and scrolling down.
Pro Keep desktop clean(er)
Instead of keeping commonly used files on the desktop, you can tuck them away to the top of the screen. This can unclutter your screen, or create more room for more icons if you like quick access to everything.

Pro Keyboard centric
SizeUp has user-configurable keyboard shortcuts for a set of pre-defined actions.
Pro Supports multiple monitors / spaces
Windows can be sent to different monitors and spaces. It can also be aligned as needed.

Pro Simple
SizeUp is easy and simple to use without having to configure.
Pro AppleScript support allows extending functionality
AppleScript permits adding features such as tiling all open windows. Additionally, FastScripts it allows the user to add keyboard shortcuts to AppleScripts.
Pro Menubar dropdown for shortcuts
Learning a bunch of keyboard shortcuts right off the bat may be difficult to remember at first, which is why a menubar shortcut for the app exists with all the shortcuts listed.
Cons
Con Can't keep visor open when typing in other applications
The unclutter visor will not stay open when working/typing in other apps. Sometimes it is desirable to use the visor to re-type things, it's not possible outside of copying and pasting, or opening and re-closing the visor.
Con $10 seems a bit much for what it does
Con Nag window
If a license is not purchased there is a nag window (which suspends function) that pops up when loading the app (at user login). The nag pop-up is also summoned at certain time intervals and by performing a certain number of commands (manually or by keyboard shortcut).
Con No on-the-fly split screen window settings
Unlike some other tiling window managers, SizeUp has no way to change the size of split screen actions on-the-fly. Any time a user wants to change how much room on the screen a window takes up when using the split screen function, they will need to manually change the settings, which can be time consuming.
