Which log processing and aggregation tool is preferable: Fluentd or Logstash?

The choice between Fluentd and Logstash depends on the specific project requirements, but generally:

• Fluentd is lighter and more resource-efficient, written in Ruby, suitable for lightweight log aggregation and forwarding. It has a simple configuration and broad plugin support.
• Logstash is a more powerful and feature-rich tool, part of the Elastic Stack, written in Java. It supports complex data processing, filtering, and transformation, but requires more resources.

If you need a simple, fast, and easy-to-configure log collection system, Fluentd is preferable. If deep processing and integration with the Elastic Stack are important, it is better to choose Logstash.