What’s the Best Easy-to-Set-Up Monitoring Software Without Alert Overload?

I'm looking for a simple monitoring software that can check uptime, hard drive space, or services on both Windows and Linux without bombarding me with too many alerts. Previously, I used PRTG, which was great because it only notified me about critical issues like devices going offline or running out of space. I've also tried several tools like Zabbix, CheckMk, LibreNMS, and Kuma, but I've found them either tedious for adding devices, lacking reliable notifications without keeping a webpage open, or too noisy and overwhelming in alerts unless I adjust numerous settings. What other tools are people currently using that are effective and user-friendly?