PostgreSQL or MySQL?
Don’t hope one tool fits all your jobs.
To choose between the two databases, you need to understand whether you need the transaction support of Postgres or the large-text-area support in MySQL.
It’s interesting that the two databases appear to be converging to meet in the middle somewhere. While MySQL is working on adding transaction support and slowly adding features like subselects, Postgres is making progress in the performance and stability.
Having foreign keys, views, subselects, and transactions can all be very attractive in PostgreSql – if you need them and you will make any use of them. If you don’t need them or won’t use them, then you’re probably better off with MySQL and its superior performance.