I have a friend who is a Red Hat Certified Engineer. I also know there is the Linux Professionals Institute LPIC-1, 2, & 3. Are there other popular ones? How do I pick one to start with?
The question is - what do you want to achieve? I would rather employ someone with some LPIC3-exams than someone boasting about NCLA or RHCSA. IMHO LPIC1 is a laugh. Admins with basic knowledge start at LPIC2. If you attend courses or do the exam directly is basically up to you. Just remember that they want to sell as many courses as possible.
But if I am really honest what really counts is experience, the ability to READ, the ability to LISTEN and the ability to work in a team.
I, too, believe in the type of admin who gets things done.