Out of the gate, I would recommend Postgres. However, choosing which database to use should come after you establish a few of the parameters that matter to y

Out of the gate, I would recommend Postgres. However, choosing which database to use should come after you establish a few of the parameters that matter to you. There is little reason to use a for-pay database unless you are doing something special with the features. Oracle for instance has some interesting text-search stuff builtin to the DB. But if you know you need that, then you are already starting to narrow the list of candidates.