If you are looking to focus on big data engineering specifically, you may want to consider learning one of the cloud-based technologies you mentioned such as AWS Big Data Speciality, Azure Data Engineer, GCP Data Engineer, or Snowflake. These are all popular technologies that are in high demand in the job market and can help you stay current in the field.

If you are looking for long-term growth opportunities, AI/ML may be a good choice as it is a rapidly growing field with many potential applications. AI/ML can also be applied to big data, so learning about it can also be beneficial for your big data engineering career.