Lot of people here with opinions about using Ubuntu as a desktop OS. Seemingly nobody here with opinions about Ubuntu as a server OS. Strange for a bunch of startup people who ship their SaaS backends on Linux servers.
Those LTS to LTS upgrades are kinda painful, but not unexpectedly so, considering you're catching up to the past 2 years of evolution in the whole ecosystem at once. On personal computers, I hate that model, but on servers, I'd much rather spend up to a day or two fixing stuff at a time of my own choosing once every two years, than spend less time fixing random issues which crop up at random intervals during a routine apt-get upgrade.
I'm not quite sure about that. If you do, at least enable logging/health monitoring. I've had unattended upgrades break services on Debian servers. I typically just keep an eye out for security upgrades and run the commands every saturday at 1 am to avoid interruptions if anything goes wrong.
I've used Alpine before and it's fine, but I want proper bash and full tools which is tedious to setup, and it doesn't do release upgrades automatically. Sometimes they make major changes like sudo-to-doas. Alpine needs a better versioning system and a release upgrader.
I've also run Debian and found it unpolished and unreliable. For no reason whatsoever package updates just randomly reset all my preferences sometimes. This has happened to me multiple times over different packages and installs. Now I wouldn't run Debian if you paid me.
Ubuntu Server has none of these problems and just works.