S3 in a single region is based out of multiple data centres / availability zone, with data distributed so that the loss of a single availability zone won't impact either data availability or durability, even to the point of being comfortable with complete physical destruction of an AZ. The same applies for Azure, GCP etc.
B2 is based out of a single DC (or at least, was at launch and I don't see anything that suggests that has changed?) You've got to decide what's most important to you. Data persistence or $$$.
B2 is based out of a single DC (or at least, was at launch and I don't see anything that suggests that has changed?) You've got to decide what's most important to you. Data persistence or $$$.