When comparing Display Fusion vs Stack, the Slant community recommends Display Fusion for most people. In the question“What are the best window managers for Windows?” Display Fusion is ranked 7th while Stack is ranked 12th.
Ranked in these QuestionsQuestion Ranking
Pro A lot of settings for every window or sub-window that opens
Pro Windows snap to each other
Especially on large monitors, you may want to have multiple windows open on the same screen. Windows only snaps 2 windows to a screen, but Display Fusion snaps windows to the edge of other windows.
Pro Allows different wallpapers/screensavers for each monitor
While Windows limits your customization to 1 wallpaper and 1 screensaver, which has limitations for certain applications. For example, if your monitors have different resolutions or aspect ratios, wallpapers don't always play nice. Display Fusion lets you have a different wallpaper for each monitor which alleviates issues like this.
In industrial applications, this means that you could have a customer-facing monitor which has a different (more professional) wallpaper and screensaver.
Pro Each window keeps its own position at startup/open
Pro Shortcuts for window management
Using keyboard shortcuts, you can lock your mouse to the confines of an area (a window, or even a specific monitor - useful for gaming), as well as resizing or moving the window. These are great additions to the window shortcuts built into Windows (alt+tab, Alt+F4, Win + D, etc).
Pro $25 for a lifetime upgrades
Pro Automated stacking
Can define a zone, that stacks all windows inside itself vertically or horizontally.
Pro Tabbed zones
Any area on the screen can be made tabbed. E.g. show a tab-like list of windows inside that area.
Pro Customizable hotkeys
Pro Supports multiple monitors
Pro Supports HiDPI
Pro Supports window filtering
Pro Easy to use with middle mouse button
Con Window splitting configuration requires manual input
The GUI for window splitting can be a bit tedious to work with - while it offers great customizability, it does require either calculating how many pixels you'd like, or trying it hit-and-miss if you'd like to i.e. fit an IM program with the contact list to a side of the screen. In other words - no real-time preview, and the splits' edges don't travel together when adjusting edges around.
Con Not nearly as useful for single monitor setups
Most of the features are useful for multi-monitor setups. If you are just using one monitor, you won't be using the majority of the features available in Display Fusion.
Con Expensive for what it offers
Starting at $25, this program won't offer much utility to most users - however it can be useful for niche users. $5 or even $10 would be an easier pill to swallow.
Con Layouts are static
Layout must be predefined
Con Need to learn XAML layout language
To create custom layouts, one needs to learn some of XAML. There's a sample, but it does not cover all configurations.