Keybinders dream. Custom functions easy to whip up and assign to a key. It has a few arcane keybind ideas like hydra, that aren't even on the radar of other IDEs. The hydra takes vim, spanks it, and sends it to bed.
The place Emacs traditionally falls short as an IDE is intelligent code completion. But with LSP this will get better.
VS Code is very different from Atom, though, so I wouldn't lump them together.
Edit: sorry, I missed the open-source requirement. But I stand by my recommendations. There just aren't that many great IDEs out there.
Indeed. Atom is very much a stripped down, get-a-plugin-if-you-want-more kind of editor whereas VS Code has a ton of functionality built in.
for everything else, Emacs ( spacemacs ) will suffice.
( if the open source requirement is removed, i used visual slickedit for many years, for many projects, before IntelliJ ).
Any particular reason you prefer open source (considering Jetbrains' tools aren't)?
What's your preferred platform?