As a person who just recently turned down an offer to write an ArangoDB book, Mongo is not worth it. I think most needs are met between Arango and PostgreSQL. A

As a person who just recently turned down an offer to write an ArangoDB book, Mongo is not worth it. I think most needs are met between Arango and PostgreSQL. Arango provides a scalable NoSQL option over PostgreSQL (let's see what version 10 holds). PostgreSQL provides a solid, efficient SQL solution. Mongo provides no benefits of transactions or solid design. If you want either, look to Arango or PostgreSQL.