When comparing Virtual Box vs Better Touch Tool, the Slant community recommends Virtual Box for most people. In the question“What are the best Mac OSX apps for someone that's new to Apple?” Virtual Box is ranked 15th while Better Touch Tool is ranked 20th. The most important reason people chose Virtual Box is:
It works for Windows, macOS, Linux, BSD, and many others.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Compatible with Many Operating Systems
It works for Windows, macOS, Linux, BSD, and many others.
Pro Beginner friendly
A virtual machine can be set up in minutes if a ISO file to load is already available.
Pro Works well and fast for Windows host and Linux guest
Pro Free and open source
Pro Many free images available
Though most are linux flavors at https://virtualboxes.org/
Oracle's virtualbox site has others.
Pro Can do snapshots
Pro A lot of customization
VirtualBox has multiple virtualization options. Each one may be tailored to the guest operating system’s needs. This makes it especially good on virtualizing older systems, such as DOS, obscure distros, etc.
Pro Endlessly customizable
Pro Extendability
Allows user to extend my MBP with touchbar by creating custom actions per app. Also supports system-wide integration (touchbar actions).
Pro BTT makes it simple to sync your hotkey, Touch Bar and gesture setup between several machines
Pro Sync settings in the cloud
Pro There's a free companion app for iOS that you can use to remote control your Mac
Pro Supports Apple script, bash, javascript
Pro Customize window button behaviour
Pro Make your own menu bar items
Pro Active community
Pro Built-in clipboard manager
Pro Highly configurable window moving / window snapping options
Pro Key sequences
Supports key sequences for things like text expansion.
Pro Supports MIDI devices (keyboards, DAW controllers, etc.)
Listen for MIDI events and have them control anything. For example you could use a DJ controller in your favorite video editor, etc.
Pro Lets you configure your external mouse's 4th and 5th button per app
Pro Record gestures / drawings and assign them to actions
Pro Developer is regularly adding features / improvements
Cons
Con Lacks video performance
Virtualbox has a hard cap of 256MB of video memory. This could make newer operating systems run slower.
Con Minimal CPU customization
You can only enable/disable certain features. You cannot cap the speed of the CPU, which is required to run systems such as Windows 95.