There is an absolute candy store of data storage services available on the GCP. You probably have seen a taxonomy like the one in the following diagram, which tells you which service to use when. Now you certainly should take the time to go through this diagram and understand each part of it, but the bottom line can be summed up as: unless you really have a strong pressing reason, just use BigQuery:

One asterisk about this preceding taxonomy is we intentionally list Datastore in the OLAP part of the tree because even though it does have a transactional mode, in the real world, if you need transactional support, you are far more likely to go with RDBMS than with a document-oriented NoSQL database such as Datastore.

What might some of those strong pressing reasons to not use BigQuery be? Well, you might need really ironclad...