ubuntu server is more than twice as widespread as Debian server, see here
That statistic seems a bit odd to me as it says Unix is twice as much more used then Linux on servers for websites????
And Centos is less then Debian, while I don't know any host using Unix.
And cPanel as second of the biggest panels, doesn't even support anything else then Centos or alike.
So from the pro panels (used by hosters) only DA and Plesk support Ubuntu. So Plesk must be pulling almost all that Ubuntu weight.
Since that statement about unix being use almost twice as much, I have a hard time trusting these statistics.
As for that second link.... seems you can't really use that in a good way... try the same and instead of using "all" select "no desktop" and see what it says then.
Same if you try the same with the selection boxes below, as soon as you select "no desktop, all the known distro's are gone.
If you select "gnome" as desktop, it's Ubuntu first and Centos second. But in this case, that's also no good selection to make because no desktop's are used.
lower running cost (less often LTS upgrades, better and more modern drivers, latest web stack parts, etc).
Lower costs? I don't know how. Except for upgrading to major OS versions and that's only if you're not using Debian.
As far as the driver upgrades, it would be comparible with Fedora which also has faster updates then Centos for example. But faster updates could also mean a little bit less stability. Not necessarily, but possible. Next to that, Debian can do the same, so why would it be better than Debian?
Since you like stats, have a look at this one:
Here are the ten most stable Linux Distros to try in 2021.
analyticsindiamag.com
You see Ubuntu on the low side, place 9, while Debian is at 2 and Fedora is 3.
I rather look at what other hosting company's use and which panels they use and which OS they use.
Most widely used is not a definition of being better, but mostly a definition of being more popular. It's not a definite proof that it's better.
Windows is most widely used on desktops way more than any other OS, does it make that better than Linux? I don't think so.
So being widely spread is not really an argument, because there also are loads of developpers and hobbyists running vps systems with Ubuntu as "server" which is counted too.
However, having that said, I don't have any doubt that Ubuntu is most populair nowadays and I certainly won't say that it would be a bad choice. On the contrary. It's a very good choice.
But on servers you would mostly like compatibility and stability. And for stability I pointed to Debian.
But ofcourse if people would like Ubuntu more, it's also a good choice. I won't go into a discussion about that.
So yes I might have made a mistake by stating that Ubuntu is not the most widely spread on servers (but I ment hosting servers, and I still doubt that most hosting servers are running Ubuntu, I could be wrong), but I still stay with my recommendation as made before. But ofcourse next to Debian, one can also choose Ubuntu. But that seems logic to me as one also can choose Fedora instead of Centos. Kind of the same situation.