What metrics do you actually track for website/server monitoring ?

There are so many things you can monitor - uptime, response time, CPU, memory, error rates, logs, etc. But in reality, I’m curious what people here actually rely on day-to-day. If you had to keep it simple, what are the few metrics that genuinely helped you catch real issues early ? Also curious: What did you stop tracking because it was just noise? Any metrics that sounded important but never r