I personally prefer systemd and moved from Ubuntu to ArchLinux a long time ago in order to use it. But I agree with you, the constant overhaul of UI is a problem which is why I have stuck to Xfce for a long time. I however, do not use GIMP, but there may be other options out there.
By the way MacOS is Unix, it is a POSIX compliant OS. Also, you can run Linux on your Mac.
And, sure, MacOS is unix-ish but Apple is ripping more and more of the old NextStep and BSDish things in favor of their own stuff with each version. As long as it just works I'm pretty happy. There are, however, lots of little quirks and gaps with their POSIX layer which is why I'd hesitate to call it a proper UNIX.
Also, you can run Linux on your Mac.
Which would be great if I wanted Linux. I don't. MacOS is working just fine for me.
OpenBSD's ftp command has become a generic multiple-protocol file transfer tool, different to the ftp commands of the other BSDs. (FreeBSD puts this functionality into a tool named fetch, instead.)
The r- commands were eliminated from FreeBSD some time ago, with much the same happening to them as happened with telnet on MacOS. They are no longer in the operating system, but are applications that one can install from packages/ports.
BSD re-vamped its command-line interface to ps in 1990. It has been getopt-based, and documented as such, for 29 years and 7 days.
rc.local was labelled obsolete in FreeBSD in 1995, and deleted from base in 1998.
And so on.