There are many many database products on the market. And many of them are great products. My focus, for the most part, has been Microsoft SQL Server and Microsoft Access. I like the Microsoft platform and have made it my target platform for solutions for many years. As the world shifts from the desktop to the web (including mobile devices) my shift has been to leveraging Microsoft SQL Server as a back end for web sites and web applications.
I have built data management solutions around every version of Microsoft Access and every version of Microsoft SQL Server. Both of these are great tools when applied to the right problem. Both can be used for multi-user solutions – SQL Server provides better performance as your user base grows and as your data set grows – Microsoft Access is a great prototyping tool to answer what-if questions about data management challenges you’re trying to figure out.