If you consider a database engine for the new project between MySQL and Postgres, choose Postgres.
Reasons are simple.
1. Postgres has stricter datatypes. If a field is integer, you cannot assign a string value to it. In the long run it makes the database data less error-prone. Frameworks+ORMs will make the code transparent anyway.
2. It supports JSON data type.
3. Postgres supports Geo calculations, why MySQL has a very limited support. Really. Many services and websites need geo calculations to count distances, proximity, etc. MySQL supports the most simple operations, but any sophisticated geo math is just not implemented in MySQL.