Ubuntu is more slower like Debian, and unstable too... For novice users is Ubuntu good because of support and forum.
https://linuxiac.com/debian-vs-ubuntu/
Any other get 50% low power on Ubuntu system: https://laracasts.com/discuss/channels/servers/ubuntu-50-slower-than-debian
CentOS is really hard to learn and end on 2021 will stopping new releases, died.
In between two I prefer the Debian Linux (many many years ago start with this, because at start ask a hacker group and recommended system say Debian, I still not know 100% sure why, but I happy, not have problems 10+ years on servers).
So don´t use Ubuntu Linux for kids at server.