Should you learn CentOS or Ubuntu for most job prospects?

CentOS is a midstream of RHEL. The upstream of RHEL is Fedora. Fedora moves very fast; CentOS moves fairly quickly with the sig work, and RHEL is a snail. Ubuntu on the other hand moves quickly all the time, although their LTS releases are snail-like as well, and their board bringup is poor.

The context missing from your question is “what kind of job do you want?”.

If you want to be a system administrator, RHEL/CentOS/Oracle Linux is the way to go, at least for the foreseeable future.

If you want to be a developer in the Red Hat ecosystem, Fedora is the way to go. You will be upgrading your system every 6 months, but Fedora moves fast! and the toolchains are always up to date.

If you want to do container development (my technical area of focus at present), sadly Ubuntu wins out here as container work is mostly done on Ubuntu systems, even at gigs like (unmentioned company:). That said, Ubuntu’s support model is not sufficient for most/many/any enterprise, so all that work ends up getting ported to Fedora/CentOS/RHEL in some way or another.

How to be System Admin Centos? 

How to master Centos?

Làm thế nào để trở thành System Admin Centos?

Làm thế nào giỏi Centos?