[byteshock]

Datadog is the best all around tool with APM and log monitoring built in. I highly recommend it as it will be substantially cheaper than paying for separate monitoring, apm, logs, etc. The support is also a lot more receptive towards small business owners unlike other platforms such as New Relic.

Also if you send custom stats to datadog such as login activity, you can use their Anomaly detection to find suspicious behavior.

Disclaimer: we use datadog at my company and have tried all the other popular options. Hands down datadog is the most feature rich and user friendly.