Ultimately most of the technical differences boil down to a single tradeoff between performance and reliability. In some use cases, you have many transactions

Ultimately most of the technical differences boil down to a single tradeoff between performance and reliability. In some use cases, you have many transactions against a data store that won't be modified once it is set. In a case like that, mongodb is acceptable. In other use cases, you have more complicated transactions involving lots of separate logical units. For example, lets say you are building an inventory and order management system. Someone wants to buy a widget. You need to reduce the widget inventory and push it into a customer's order, essentially an "Atomic" operation. AFAICT there's no "simple" data model under which MongoDB can give you atomicity. In order to make a decision, the best bet is to figure out those requirements and just try one that fits the bill.