I use VSCode. It does everything I need it to and has enough plugins for different languages to satisfy the most diverse of stacks. I particularly like the way it works with TypeScript to show me auto-complete hints when I start typing a class name, the linting 'fix-on-save' stuff it can be set up to do, and the nice tight integration with GitHub (and, more recently, Team Services).
Can't beat it for a piece of free software IMO.