- Visual representation of data structures

- Navigating in binary libraries

- Architecture diagrams with two way editing

- Integration with ticket and source control systems, so that I can relate an issue with a branch and respective set of changed lines of code

- Live unit tests

- Live static analysis, as one types

- Incremental compilation, when hitting run almost everything is pre-compiled

- SQL database integration, ER diagrams, OR mappings generation

- Management of server instances and cloud services

- Memory profilers

- GC tuning tools

- Code metrics

- Graphical debuggers for GPGPU programming

- Graphical debuggers for threads, tasks and processes

- Handling of processes as single project for micro-services debugging

And a couple of other stuff, basically the kind of goodies one gets with Visual Studio Enterprise.

- find definition

- find usages

- rename

- extract method

- detect code duplication

- highlight unused symbols(vars or functions)

- understand frameworks and libraries

- can suggest useful transformation or code simplification

- Intellij can understand type documentation like JSDoc and PHPDoc and use it in completion and highlight errors if using the wrong type or object member

- smart spellchecking, spellchecking that understand when it is in a comment or if it is a symbol name

- good VCS support(diff, commit, push)

- good debugging support

- IDEs have by default a lot of linting and code analyzing tools setup, trying to go from Intellij to VS Code defaults is a big downgrade , maybe it could be partially fixed by installing many plugins but I personally want to pay for a good program made by professionals and keep them profitable(and not have JetBrains fail or get bought by Google or Microsoft)