This is a relatively fresh reinstall, and I've only been adding gestures as they come up [0] -- so this should be pretty representative of my top usage (slightly reordered for organization):
I think I can say with a fair amount of confidence that 3 Finger Tap (open in new tab), Pinch In/Out (close/open tab), and Rotate Left/Right (change tab) are my most used custom gestures.
With 3 Finger Swipe Left/Right (back/forward) configurable in vanilla system preferences, but done in BTT for consistency, and 4 Finger Swipe Up (Show Desktop)/Down (Mission Control) with their directions reversed from the system defaults [1].
Really, every one of the gestures on there is pretty indispensable to me feeling comfortable using a computer. Going back to keyboard shortcuts for the same actions (eg, when I'm using someone else's computer) feels like hunting-and-clicking menu items with a mouse.
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[0] Import/Export is a thing, but I usually use a reinstall as an opportunity to tighten things up.
[1] Because this way makes way more intuitive sense to me. Swipe Up = Swipe Away = "GTFO windows". What hell, Apple HCI engineers?
I enjoy BTT bunches and use a non-apple keyboard/mouse.
Rebinding the f1-f4 keys to tab navigation (previous, next, close tab, new tab) works well. Rebinding extra mouse buttons to get gestures back on non apple mice (tilting scroll wheel to smart zoom). Other setups would be neat to hear about.