Which OS to choose?

Most Popular Linux Distributions:

Debian

Debian is a totally free, non commercial distribution of Linux. It remains true to the original concept of Open Source software. Debian focuses on stable releases that work without problems on all platforms.
This widely respected project is still releasing new versions of Debian, but it’s known for moving much more slowly than distributions like Ubuntu or Linux Mint. This can make it more stable and conservative, which is ideal for mostly systems.

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Ubuntu

Ubuntu is usually the distro of choice for new users, as it tends to focus on usability and simplicity for the user who wants the system to "just work". The Ubuntu project has a focus on providing a solid desktop experience.
Ubuntu is probably the most well-known Linux distribution. It is based on Debian, but it has its own software repositories. Much of the software in these repositories is synced from Debian’s repositories.

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CentOS

CentOS is a community project that takes the Red Hat Enterprise Linux code, removes all Red Hat’s trademarks. CentOS previously operated as a free downstream distribution from RedHat Enterprise Linux.
The last supported version of CentOS has support until 2024, so CentOS users still have some time to consider using AlmaLinux or another Linux distribution.

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AlmaLinux

AlmaLinux is a free CentOS replacement created by the CloudLinux team. CloudLinux is a downstream distribution of RHEL, meaning the team already has considerable experience maintaining a RHEL clone. AlmaLinux will be community-driven by the AlmaLinux foundation. The software used by AlmaLinux is intended to be 1:1 binary compatible with RHEL and CentOS (non-stream).
Aside from the name, there are very few differences between AlmaLinux and CentOS. The CentOS project is backed by RedHat, and the AlmaLinux foundation is backed by CloudLinux. While the backing companies are different, the communities they support share near-identical goals.