Linux distros: Ubuntu Server → Debian. (CentOS for educational purposes only.) Maybe Arch (or Gentoo) in the future.
Basic Path: Linux, Command-line & Shell scripting, Python programming, Security, Networking (Cisco, HP, Juniper), Virtualization, and High Availability. See IT Certification Roadmap.pdf for more info.
Programming Path: JS, Python, PHP, Ruby, C, C++, Go, Java, Swift, Rust, Scala, C#.
Certifications:
SysAdmin