alt+tab. Used to work perfectly. Now broken. I've returned to debian stable, which comes with a gnome-2 legacy option that works out of the box just as well as it did a decade ago.
Go to [0], install, configure to either "all windows" or "all windows in current workspace", and alt+tab probably works like you want again. It's not terribly difficult.
[0] https://extensions.gnome.org/extension/15/alternatetab/