"While the certifications serve to increase your knowledge of the [environment] you work with, the harder courses will be better recognized and will naturally grant more knowledge," Millen said.

HP software consultant Geoff Kingsmill, who has completed the Red Hat Certified Architect (RHCA), which is Linux's highest certification, said content difficulty is a good gauge in determining value.

"I didn't set out to do a certification - I set out to learn something," Kingsmill said. "Exam-based courses mean you need to know everything about the content [so] you can't just passively listen but you need to synthesize to truly learn.

"Pick the certifications with harder exams because although you will kick, curse and scream, you will come out a lot more educated."

Kingsmill believes Linux-based courses offer more technical training than competing certifications.