Wild statement, imo. There is no better open source database, so I'm very curious what you prefer and what your use cases are...
All the eng. managers I've worked with in the last decade have sworn by Postgres, in the decade before that they were swearing at mongo and getting betrayed by Arangodb switching to a restrictive license and seeing other innovative databases going down the same path means for new side projects I go postgres.
Postgres doesn't do replication, HA or columnar/OLAP workloads, for example.