Objects / documents / "key-value". If the data is small enough to fit on a single application server node, it seems to me that the relational model is likely overkill. But I don't doubt that there are good counter-examples to this, it's just my intuition.
Key-value pretty trivially fits into the relationship model if need be. But yeah, if you’re very sure of the key-valueness of your data, something like RocksDB could be a more direct fit. It’s just a little harder to work with in my experience.
