Hey, I am one of the maintainers of SigNoz. ELK is tightly coupled to Elastic which may not be the ideal database to handle opentelemetry data. We wanted to be more of a platform where we can provide different DBs as plugins. Users can also build their own usecases by building more stream processing applications.

On the other hand, Druid powers analytical queries on data and is efficient in handling high-dimensional data. Many companies use Druid at scale (https://druid.apache.org/druid-powered).

Also Jaeger, a distributed tracing tool, provides plugin for cassandra, elastic, badger, etc. Some users found limitation in running fast aggregation of filtered traces. With Druid we can now search by annotations(without need of service name) and get aggregates on filtered traces, like p99 of version=xyz filters.