Prefect
Modern Python orchestration — Jeremiah Lowin (ex-Airflow contributor), 2018. "Negative engineering": focus on what has to be solved for Python jobs to run safely in production.
Decorators (@flow, @task) instead of DAG object construction. Asynchrony built in. Prefect Cloud is managed; Prefect Server is open source. Supports dynamic flows (workflow structure built at runtime).
Competitor: Airflow (mainstream), Dagster (types + assets). Prefect wins when teams want a Python-native API without DAG mentality.