Which Linux OS Is Best to Start Learning?

Hi guys, I am technically not new to the forum but have been lurking and reading some of the tutorials present. I want to become a more active member of this immensely beneficial community. My background I work as a network engineer, even though I still see myself as a beginner. I want to become more knowledgeable in terms of IT Security. To reach that goal I know it is required for me to become more proficient in linux terminal and linux scripting, So which OS would you advise for me to install on my desktop to play with? should I go straight in and install Kali Linux or perhaps start off with something else like ubuntu or cent OS ?