I still miss features from AmigaOS, to the point I've started adding some to my software. E.g. I've added "assigns" to my shell (very superficial integration), and it's so nice to be able to just create an alias for any path.
It's hard to explain why it feels better, because you could "just" create a bunch of symlinks in one location, but being able to "cd projects:" instead of ~/Desktop/Projects just feels nicer. I've also added "implicit cd" when entering paths, so I can also do just "projects:" like on the Amiga.
What made the Amiga special wasn't just the hardware, but a whole host of small extra niceties like that.
Another favorite is datatypes: A uniform plugin-based API to open files of any type, ensuring Amiga software written decades ago can open modern image formats.
And another one I love was the ability to open a new console window as a file path, so you could redirect shell output to a new window just as if it was a file.
(it also took way too long before I remembered who Alex P. Keaton was...)