Here are some of the extensions I find useful with VSCode:
CPP Tools: The official extension for working with C++ code. Automatically indexes all code in the currently open directory, offers auto-completion and syntax highlighting.
Python by Don Jayamanne: There are many Python extensions, but this seems to be the most popular one. Syntax highlighting, indexing and code completion.
Vim: There are many Vim extensions, but this seems to be the most popular one. It has entire universes to traverse before it can be as good as Vrapper, the Vim extension for Eclipse. This VSCode extension offers very basic navigation and editing commands.
Git Blame: This extension does one little thing that I need everyday to work with code from other people: know who modified a line of code. This extension shows that for the current line in the status bar.
Matlab: I need to regularly browse through some MATLAB files. This extension offers syntax highlighting of Matlab files.
Tried with: Visual Studio Code 1.4 and Ubuntu 16.04