How can I reliably and authoritatively determine which of the predefined "generic" X11 keyboard layouts is the best choice for my physical device? There must be a better way than counting keys and guessing whether it should be "intl" or not "intl".
Most keyboards with a US layout are either 101-key or 104-key, depending on whether or not they have the two Meta/Super/Win keys and the Menu key. Standard "international" keyboard layouts are 102-key and 105-key.
If you're using a modern keyboard with a number pad and a US layout, it's most likely a 104-key.