u/ArgentStonecutter

Dear everyone who produces or sells keycaps...

If you have an ISO enter key, you also ought to provide 1u <>, \|, \@, #~, and at least enough alternate-legend numeric row keys to let someone populate their boards for US-ISO and UK-ISO at a minimum. Probably both R2 and R1 versions of \|if your profile requires it.
And a 1.25u left shift.
Which brings us to the next point... there are layouts that need 1u, 1.75u, and 2u shift keys as well.
65% and 75% layouts will need to populate the navigation column, so include all the row alternates for home, end, page-up, page-down, and delete.
And 1u right modifiers, at least including alt/opt, function, and control, and ideally win/cmd and menu as well.
And some kind of alternate for the "Windows" key for people not using Windows.
For keyboards with an f13 key, include at least an f13 and a del.
For split backspace, all top row 1u versions of delete, backspace, and \|.
And if you add a 1u tab and enter to all the above, then ortho keyboards will be happier.
And 2.25u and 2.75u and maybe 1.25u convex bottom row keys for split spacebar variants.
And media keys for 108-key layouts.
And if you have an R5 row, both heights of escape.
Once you've done all this, then you can start adding flowers and panda faces and dancing stick figures and other novelty keys to pad out your selection.