I've got that action keybound to alt-space on my desktop.
Which would be WindowMaker.
Key benefits: virtually no development, Steve Jobs designed it, but for engineers on UNIX (well, NeXT), not idiots, and it's ~20 years old, so it's balazzzzzingly fucking fast on modern HW.
Stays the fuck out of my face, lets me get shit done.
When I first saw a fully customized WindowMaker in 2002, I thought, "Wow, HollywoodOS does exist!" Back when Linux used to come with several functional desktops, AfterStep and WindowMaker (both clones of NeXTStep) were my favorite, followed by Enlightenment (the only place I've ever seen window buttons on the side of the window).
I've played with a lot of desktops. twm, fvwm, fvwm2, WindowMaker, Enlightenment, icewm, various *boxes, GNOME and KDE through the ages, and XFCE4.
The latter is probably the closest to a replacement to WindowMaker that I've found, but it has two serious deficits:
1: No "raise on circulate" (with window contents visible) when you're alt-tab circulating through windows. Makes it really hard to find what you're looking for.
2: No pinnable window list. In WindowMaker, any arbitrary menu (or sub-menu) may be pinned to the root window. F11 (or middle mouse on root) brings up a menu of all open windows (the windowlist), which can be navigated (arrow keys or mouse), and if pinned, stays persistent while you hunt down the particular window you're looking for. Very useful when needed.
Which would be WindowMaker.
Key benefits: virtually no development, Steve Jobs designed it, but for engineers on UNIX (well, NeXT), not idiots, and it's ~20 years old, so it's balazzzzzingly fucking fast on modern HW.
Stays the fuck out of my face, lets me get shit done.