I switched from CentOS/RHEL to Ubuntu on my servers a couple years ago
While it was a little jarring to have things named and located differently (not much different, but different none-the-less), I was basically "Ubuntufied" within a couple weeks
20 years ago I ran SuSE almost exclusively
Prior I had Slackware (which is still around, and distinctly non "corporate"), RedHat, Mandrake, and a couple others
You wanting to avoid "being ruined by corporate interests" is likely impossible - unless you go with a single BDFL distro like Slackware
Ubuntu is "corporate"
RedHat is "corporate"
SLES is "corporate"
Debian is "corporate" (not as in a commercial entity, but definitely have their own very tight community (ie "corporate") rules as to the "right" and "wrong" ways of doing things)
I'm curious as to why you think Ubuntu (or Red Hat, or any of a number of other distros) which have been around "a long time" won't continue to be around for "a long time"?
Ubuntu's 18
Debian's 29
Red Hat is 30
Suse is 31
...what are you looking for, exactly, that you think isn't handled well-enough by the "big guys"?