DbSchema Pro is an excellent tool for the price. It is attractive, intuitive, and includes the features that are most important to me without adding a lot of complication that I see in more "enterprise" level tools. I can quickly and easily put together a conceptual ERD either connected or not connected to a database, then either connect to generate the schema in the database or generate a sql script. Then I can easily make updates either to the model or to the database and keep them synchronized. I can easily switch connections in order to push changes to multiple environments. The graphical representation is simple and elegant, presenting all the important information without a lot of noise.