Modern OpenGL? App store with useful apps?
But that's nothing that affects me personally. What bugs me about macOS is how sloppy, buggy and limited it has become. Finder sucks big time. SMB doesn't work all too reliably. Wanna domain join - tough luck. (Even Linux distros are advanced in that area - Gnome 3 on Fedora allowed me to setup Enterprise Login and just entering ID / Password for my AD account during initial setup and it all worked flawlessly!). The OS updates are atrociously slow - at least they are infrequent but just goes to show how much attention they're really paying.
That's just from memory - I haven't used it for last year.