SQL Server Installation choices
Install the tools you need now, and no others.  You can always add more features to the installation later.

If you're not installing reports or PowerPivot into your existing SharePoint installation, don't install them.

When most people say that they want to get "SQL Server" installed, they mean just the database engine.  If that sounds like you, install the Database Engine and Management Tools, and you'll have a basic SQL Server up and running.