Backend database and user management

I am using Photon Cloud to develop a RPG game with huge open world in Unity. How is the backend database going to work? what database will you recommend me to use?

I recently discovered playFab as backend user managment for game, but I guess it is hosted on playFab’s server. What do you think the pros and cons?

Another option for user management is Strapi ( There’s no monthly fees and you can manage everything yourself.

I’ve created a Unity asset which makes integrating with Strapi easier: Strapi for Unity | Integration | Unity Asset Store