The main issue today is hw support and power saving: IllumOS/OmniOS, FreeBSD could barely run on modern hw and even if they run they tend con consume much more electricity than GNU/Linux.
Beside that instead of becoming fool with Ubuntu I'd rather choose NixOS or, if I can depending on the infra needs, Guix System to have a more manageable system language. They are MUCH more manageable and robust than Ubuntu or other GNU/Linux distros by nature, not stable as old SUN Solaris, but still stable enough and they teach how to manage modern systems and infra, witch is damn needed these days.
Beside that instead of becoming fool with Ubuntu I'd rather choose NixOS or, if I can depending on the infra needs, Guix System to have a more manageable system language. They are MUCH more manageable and robust than Ubuntu or other GNU/Linux distros by nature, not stable as old SUN Solaris, but still stable enough and they teach how to manage modern systems and infra, witch is damn needed these days.