It bugs me that nobody -- nobody -- makes an error-free Mac layout for aftermarket keys. WASD comes really close, but mislabels the key above forward-delete as "insert", even though that should be the "help" key. Most everyone else does nothing with anything other than the command key, not even bothering to make a proper "option" key. (The Mac has no "alt" key!! That secondary label is there for Windows applications, basically.)
I'd love to see a Matias-style Mac layout with all the modifier states on each key, so you can just look and see that option-2 is ™, for example.
P.S. I let WASD know about the error in their layout, since it should be easy to fix, but they didn't seem particularly interested. I also suggested a full-modifier-states layout, but they replied that they wouldn't even consider it.
I totally agree with all you said. However, with WASD, you can easily create your own key layout. As I'm pretty sure I'm going to get a WASD keyboard, I figured I'd get one with their keycaps to see the quality. And, since they can do one-off completely custom keycaps, I I took their default Mac layout and I've added several things to make it even more "Mac friendly". I've added the symbols for Command, Option as well as Control, Shift, etc and added the multimedia, volume, brightness, etc symbols to the function keys. I think it looks pretty good (mockup attached).
I considered changing the Insert key to a Help key but it seems Macs no longer have Help keys so I left it as an Insert. At least it will be correct when using the keyboard on Windows (Parallels). I also thought about making it the Eject key (and still might).
At first I was going to keep the function key symbols in the same place as the standard Apple keyboard, but it seemed to make more sense to move them around a bit since the function keys on the WASD will be in groups of 4 unlike on an Apple keyboard.
I considered added the symbols for the modified alpha keys like the Matias but I'm not sure I actually like that look. But, it would certainly be doable with the WASD custom layouts.
Or, maybe white and black keys, such as this: