@User Few points:
1. Promtheus + Grafana doesn't give tracing by default
2. If you want to set up tracing, takes time to set up and then metrics & traces don't interact seamlessly if you have metrics in Prometheus & Tracing in Jaeger
3. Even for metrics, getting Application metrics in Prometheus takes effort, while it is out of the box in SigNoz
4. You can't do things like custom aggregates over traces
5. No service map