I would begin with my own needs - Why is it that I need a monitoring solution? - What visibility or feedback do I need and why? - Are my needs of a technical nature - like finding and resolving challenges before they become outages, or are my needs business-driven, e.g.…

My apologies, I have not worked with Icinga, ever, and Nagios only briefly – too briefly to offer an opinion. I am, personally speaking, now a Netscout man and I am sure that Netscout could and would provide a solution to your question that would knock his socks off, blow…