BTT is one of these gems that really change the way you interacts with the computer. I use it so intensely that a Mac without it seems much harder to tame. Using BTT since it was a free alfa. It only get better and better, with quick update cycles that keep it up to the latest macOS and other apps.
The facilities BTT provide are so wide I would need three or more tools to replace it. The improvements it did to my workflow:
• to tap instead of clicking the mouse and the trackpad;
• to add a double-click with middle-click and middle-tap gestures;
• to launch frequently used apps with gestures;
• to position and organize windows through simple shortcuts;
• to trigger with keyboad shortcuts inner commands in several apps (like text case control, formatting options, or any command without built-in shortcut);
• to launch a sequence of apps or open selected files through a simple shortcut (like to adjust music tags and artwork running iTunes, Yate, Photoshop, Covered and the music folders);
• to do with a single command operations which mix several key types and mouse clicks (like changing view options in iTunes or using saved substitutions for rename tool in Path Finder);
• to do a sequence of operations otherwise available just manually or through scripts, like commands in InDesign, Acrobat or even Finder.
And, as one can easily see in the version history, BTT developer is always improving and polishing it.