I rate syslog-ng 10 out of 10. It's free and easy to use. It has built-in tools that help us index the various logs sent to it. It's a solid log product. If you're looking for a SIEM solution, syslog-ng will work as a stopgap measure at beginning of the project. It can also work as an injector for a true SIEM solution. You can send all the logs to syslog-ng and forward all the data to the SIEM solution after you've cleaned up the data and got the pertinent information. It's a good front end for a commercial SIEM solution, which becomes more expensive as you load more data into it. I would highly recommend syslog-ng for that use case. However, if you lack the expertise, you might need to go with a cloud-based SIEM instead. You need some in-house expertise or an outside consultant to manage it and set it up.
