Nagios Log Server facilitates the ability to search all entries of logs in a quick and easy way. Beyond that, it has allowed us to configure alerts for notification when there are potential threats (may they be security threats or only application-side problems), and to filter the data for audits and compliance.
As a 3rd party endpoint, SolarWinds Papertrail did exactly what it needed to. My hesitation is on the technical aptitude of the colleague receiving the recommendation, as the overall level of command line skill/understanding would have to be high. Web applications are a great solution here, but MOST of them already provide some sort of logging output. The scenario would definitely be in the situation where logging wasn't readily available in the current solution space. IF something like SolarWinds Papertrail was needed, it's probably the de facto thing that I would recommend.
It's extremely easy to use. I and new colleagues have never had any issues configuring this tool or setting it up, it works almost out of the box with very simple instructions to follow to configure it to our own environment. I would highly recommend it on that ability alone.
Nagios support is decent. Nothing bad to say about them, but nothing extraordinary too. We mostly asked them questions instead of actively asking them to change or fix things for us. The response time is OK, commonly you can get a response in the same day. You can also call, but they are available only during US office hours.
I honestly have never had the need to use the support team, as we have not run into any issues so far. If we did however, judging from how the tool itself works, I don't doubt that the team would provide excellent support for any issues that we may possibly run into.
Windows Event Log doesn't have 10% of the capabilities of Nagios Log Server. No real-time alerts, no scheduling, no external plugins or APIs. Nothing. The only advantage is that it is a native Windows application.
CloudWatch, by itself, is terrible at search. CloudWatch Insights works great and has powerful search capabilities, but it's more difficult to set up alerts. Also, because Insights charges per search, you have the potential to accumulate a large bill if you need to do many searches. I like that SolarWinds Papertrail has a known monthly cost.