Richard Douglas has a great post on things to think about when evaluating a monitoring tool:
A question that often comes up in meetings is, “What would success look like?” To me, it’s my favourite football team Spurs winning the English Premier League! This is never a popular answer to the person asking the question in the meeting, but generally raises a few smiles and lightens the mood. However, you’re more likely interested in monitoring software and what success means in that scenario. As I see it, success means finding an outcome that is beyond doubt. Now success could mean that the software you are evaluating is not as good as the current incumbent. That is a successful outcome. You have decided that you already own the best solution for you. Congratulations! It can also mean that a particular solution meets all of the criteria needed by your business in order for it to solve technical issues and to grow.
The advice is vendor-agnostic and is worth reading if you plan to evaluate monitoring tools anytime soon.