It has been a while since I did anything with PostgreSQL, but I remember it fondly. It was always a solid workhorse and easily filled my perceived needs for a 'real' database in projects while MySQL seemed too light. Since I haven't used it in a while, I thought it worth looking into how mature the tooling around it has become.
You can access PostgreSQL data from .NET by using Npgsql. The project includes Entity Framework Core and EF 6.x integration. Visual Studio Integration is handled by the Npgsql PostgreSQL Integration plugin. You can easily manage your PostgreSQL database using pgAdmin. There are some very good modeling tools available, pgModeler looks like a best of breed. You can even run PostgreSQL in the cloud using Amazon RDS for PostgreSQL.
It looks like the tooling has continued to mature. Now I just need a project to use it on. :-)