Where each is relatively distinctive
n8n is relatively distinctive for visually inspecting multi-step integrations and execution history. Activepieces is relatively focused on a connector-oriented builder that can make common service automations approachable. Windmill is relatively prominent when scripts, internal tools and workflows need to live close to an engineering workflow. These descriptions identify emphasis, not an overall ranking.
Where each fits
Use n8n for integrations where a non-author can trace triggers, transformations and destinations. Consider Activepieces for repeatable service-to-service tasks with a connector-first mental model. Consider Windmill when the workflow needs code, typed inputs or a small internal interface. A workflow is a product surface for its operator, so the operator should be part of the evaluation.
Boundaries and ownership
All three still leave you responsible for credentials, retries, duplicate side effects, upgrades and external API changes. Read the current license and hosted-service terms for the exact version you plan to use. A visual editor can make a sequence easier to see, but it can also hide error semantics if the team never tests failure and replay.
A comparison you can run
Implement the same flow in each: receive a webhook, validate a payload, call one external API, write one record and notify a test channel. Break the API call, replay the run and inspect the resulting logs. Compare repair time, credential handling and duplicate prevention rather than counting features.