I like the fonts of all of them. #6 looks more like a guitar, which is not part of our program. #4 is perhaps trying to do too much in the AHS, and we have instruments that use clefs other than treble.
It took me a bit to get used to it, but 13 works. I like the simplicity of the instrument. I also like 14-16 as concepts. Perhaps more vertical than we were thinking on all of them, and maybe a bit too detailed in the instrument.