I wish I could stick to one editor but there is always some editor that does a way better job at a particular task. Each editor has its killer feature. I have tried turning emulation of emacs/vim on many editors to provide consistency and its never been really good. Thus I have several "default" keybindings in my head.
Because of this I try not to rely on too much magic or customization that any editor provides and instead write lots of shell scripts (Bash, Groovy and Python) to do code generation and to find things.
But I'm always wondering ... could I be more efficient by sticking to one.
VSCode will probably just become another editor I have lying around. Probably for Typescript.
I think switching between Emacs and Vim is a good idea but more a question of keeping your hand/mind coordination flexible for different input paradigms. I'd be skeptical that they're really that different in terms of efficiency for a task, but I'd say learning both really well will make you more efficient in general.
(I actually keep both open; Java files I edit in Eclipse, but pretty much anything else goes to Emacs. I also have Emacs keybindings and Emacs+ plugin installed in Eclipse.)
The only thing that trips me up really is switching from vim to one of those others, and I sometimes run vim modes in those.
One of the major reasons I keep vim in my repertoire is that it is on every machine I have to SSH into and it can handle monstrous files. Vim is also better at editing config files (SSH ops stuff) in general since you are typically manipulating and not creating content.
That said, learning new keyboard commands is sometimes a real PITA. When I'm tired, I sometimes find myself trying to close Visual Studio or Sublime Text with :q.
For a task I'll use whichever editor needs to least amount of learning, re-learning, and fiddling.
It amazes me that there was a time where I learned Emacs just for Clojure.
 Every few years I'll try an IDE. I've been doing this for over twenty-five years. I've yet to find one that I like. Over time, my bar for "what I like" has fallen to the point where now it's "it doesn't crash when loading a simple one file program." 
 The C/C++ "version" of Eclipse. I tried using it to help browse a C++ application at work. It never worked.
My favorite place to work right now is on OSX. It's Unix so you get all the command line goodies plus it has a very good GUI and great tools in the graphical environment as well (I'm thinking of XCode). Plus, I think Objective-C is pretty neat.