I've been using JetBrains IntelliJ and PyCharm for a few years as a developer, and I've tended to use PyCharm to write my articles in Markdown (because I also use Python to create the diagrams). I have no doubt Vim is great too.

For LaTeX I'm using TexStudio at the moment, because JetBrains support didn't seem quite as good. TexStudio has reasonable autocomplete for references (you can automatically add a link to the next/previous reference).

I tried Overleaf, it is very good. But I like to keep the master source of my documents on my own machine, where it gets backed up automatically. I found with Overleaf there was the possibility of getting out of step, which put me off.

Overleaf probably comes into its own when you are working collaboratively as you say.

We all have our own ways of working, of course.